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University of Michigan
1.
Ball, Nicholas Dewayne.
Synthesis and Reactivity of Palladium Trifluorides and Fluorides Towards Aryl C-CF3 and C-F Bond Formation.
Degree: PhD, Chemistry, 2011, University of Michigan
URL: http://hdl.handle.net/2027.42/84650 
► The installation of carbon–fluorine and carbon-trifluoromethyl bonds in organic compounds can have a significant effect on the chemical and biological of the molecules. However, synthetically…
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▼ The installation of carbon–fluorine and carbon-trifluoromethyl bonds in organic compounds can have a significant effect on the chemical and biological of the molecules. However, synthetically the selective incorporation of C–F/C–CF3 bonds into important biological targets remains a significant challenge. Palladium catalysis has been extremely successful in the selective incorporation of C-X (X = Cl, Br, I, OAc, Ar, N) bonds into molecules. Thus, an attractive strategy would be to utilize palladium C–X coupling methodologies to promote C–F/C–CF3 bond formation.
This dissertation will discuss structural and mechanistic studies of palladium intermediates modeling Pd(0)/Pd(II) and Pd(II)/Pd(IV) catalytic systems towards aryl fluorination and trifluoromethylation. Structural analysis of Pd(II)-fluoride complexes will be presented focusing on the affects of steric and electronics on the metal center and the implications towards Pd(0)/Pd(II) Aryl–F coupling. Additionally, the reactivity of aryl Pd(II)–F and Pd(II)–CF3 complexes with stoichiometric quantities of electrophilic fluorinating agents resulting in Aryl–F and Aryl-CF3 bond coupling will be discussed. These reactions proceed to generate both electron rich and electron poor aryl fluorides and trifluorides in good yield. Observation of C–F/C–CF3 bond coupling from isolated sigma-aryl PdIV–F and PdIV–CF3 complexes will emphasize the viability of C–F/C–CF3 bond formation in a Pd(II)/Pd(IV) catalytic system.
Advisors/Committee Members: Sanford, Melaine S. (committee member), Dotson, Garry Dean (committee member), Matzger, Adam J. (committee member), Wolfe, John P. (committee member).
Subjects/Keywords: Palladium(IV); Organofluorines; Reductive Elimination; Catalysis; Chemistry; Science
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APA (6th Edition):
Ball, N. D. (2011). Synthesis and Reactivity of Palladium Trifluorides and Fluorides Towards Aryl C-CF3 and C-F Bond Formation. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/84650
Chicago Manual of Style (16th Edition):
Ball, Nicholas Dewayne. “Synthesis and Reactivity of Palladium Trifluorides and Fluorides Towards Aryl C-CF3 and C-F Bond Formation.” 2011. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/84650.
MLA Handbook (7th Edition):
Ball, Nicholas Dewayne. “Synthesis and Reactivity of Palladium Trifluorides and Fluorides Towards Aryl C-CF3 and C-F Bond Formation.” 2011. Web. 07 Mar 2021.
Vancouver:
Ball ND. Synthesis and Reactivity of Palladium Trifluorides and Fluorides Towards Aryl C-CF3 and C-F Bond Formation. [Internet] [Doctoral dissertation]. University of Michigan; 2011. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/84650.
Council of Science Editors:
Ball ND. Synthesis and Reactivity of Palladium Trifluorides and Fluorides Towards Aryl C-CF3 and C-F Bond Formation. [Doctoral Dissertation]. University of Michigan; 2011. Available from: http://hdl.handle.net/2027.42/84650
University of Michigan
2.
Sormunen, Grant Jari.
Nickel-Catalyzed Reductive Couplings of Aldehydes and Alkynes: Controlling Stereochemistry and Regioselectivity using N-Heterocyclic Carbene Ligands.
Degree: PhD, Chemistry, 2011, University of Michigan
URL: http://hdl.handle.net/2027.42/84655
► Allylic alcohols are a common substructure in natural products and useful intermediates for a variety of organic transformations. One of the most direct synthetic approaches…
(more)
▼ Allylic alcohols are a common substructure in natural products and useful intermediates for a variety of organic transformations. One of the most direct synthetic approaches for the synthesis of allylic alcohols is the reductive coupling of an aldehyde and an alkyne. While many different methods have been developed, the use of N-heterocyclic carbenes as ligands in nickel-catalyzed aldehyde-alkyne reductive couplings has allowed the reaction to be synthetically useful for a broad range of substrates. In this body of work, strategies for both enantioselectivity and regioselectivity using N-heterocyclic carbenes as ligands will be discussed.
A new N-heterocyclic carbene ligand, analogous to ligands used in asymmetric ring-closing metathesis, was developed that exhibited high enantioselectivities in the asymmetric reductive coupling of aldehydes and alkynes. Its scope was examined for a wide variety of intermolecular couplings as well as a macrocyclization.
Advances in the control of alkyne regioselectivity have been made, with the ability to produce either regioisomer, with the complementary use of small
cyclopropenylidene carbene ligands or highly hindered N-heterocyclic carbene ligands. Regioselectivities were typically quite high in cases where the standard conditions were unselective. In some cases with strong substrate biases for a single regioisomer, the opposite regioisomer was achievable using our highly hindered N-heterocyclic carbene ligands.
Finally, studies to combine these two concepts, regiocontrol and enantiocontrol, were executed, exploring N-heterocyclic carbene ligands which allowed for the both high regiocontrol and enantiocontrol within aldehyde-alkyne reductive coupling. Advances were made in the understanding of the impacts of different N-aryl substitutions and backbone structures on both regiocontrol and enantiocontrol.
Advisors/Committee Members: Montgomery, John (committee member), Dotson, Garry Dean (committee member), Sanford, Melaine S. (committee member), Wolfe, John P. (committee member).
Subjects/Keywords: Nickel-Catalyzed Reductive Couplings of Aldehydes and Alkynes: Controlling Stereochemistry and Regioselectivity Using N-Heterocyclic Carbene Ligands; Chemistry; Science
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APA (6th Edition):
Sormunen, G. J. (2011). Nickel-Catalyzed Reductive Couplings of Aldehydes and Alkynes: Controlling Stereochemistry and Regioselectivity using N-Heterocyclic Carbene Ligands. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/84655
Chicago Manual of Style (16th Edition):
Sormunen, Grant Jari. “Nickel-Catalyzed Reductive Couplings of Aldehydes and Alkynes: Controlling Stereochemistry and Regioselectivity using N-Heterocyclic Carbene Ligands.” 2011. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/84655.
MLA Handbook (7th Edition):
Sormunen, Grant Jari. “Nickel-Catalyzed Reductive Couplings of Aldehydes and Alkynes: Controlling Stereochemistry and Regioselectivity using N-Heterocyclic Carbene Ligands.” 2011. Web. 07 Mar 2021.
Vancouver:
Sormunen GJ. Nickel-Catalyzed Reductive Couplings of Aldehydes and Alkynes: Controlling Stereochemistry and Regioselectivity using N-Heterocyclic Carbene Ligands. [Internet] [Doctoral dissertation]. University of Michigan; 2011. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/84655.
Council of Science Editors:
Sormunen GJ. Nickel-Catalyzed Reductive Couplings of Aldehydes and Alkynes: Controlling Stereochemistry and Regioselectivity using N-Heterocyclic Carbene Ligands. [Doctoral Dissertation]. University of Michigan; 2011. Available from: http://hdl.handle.net/2027.42/84655
University of Michigan
3.
Matsuura, Bryan Shigeru.
The Development of Transition Metal Catalyzed Reactions for Applications in Complex Molecule Synthesis, Methodological Development and Biomass Processing.
Degree: PhD, Chemistry, 2015, University of Michigan
URL: http://hdl.handle.net/2027.42/116626
► Described herein are four projects: Chapter 1 will discuss the development of an intermolecular C–H functionalization of indoles with diethyl bromomalonate mediated by the photoredox…
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▼ Described herein are four projects: Chapter 1 will discuss the development of an intermolecular C–H functionalization of indoles with diethyl bromomalonate mediated by the photoredox catalyst, Ru(bpy)3Cl2. The direct functionalization of indoles is of interest to the greater synthetic community due to their ubiquity within the natural world. The difficulty in developing an intermolecular radical alkylation reaction is principally due to competitive side reactions such as reductive dehalogenation. Our approach enables a room temperature alkylation of a wide variety of electron rich heterocycles that is high-yielding, scalable and functional group tolerant. Chapter 2 will describe the development of an unusual vicinal olefin difunctionalization reaction using high-valent palladium catalysis for the synthesis of highly functionalized spirocyclohexadienones and polycyclic aromatic compounds. This synthetic approach has applications in the total synthesis of the antibiotic platensimysin. It will also provide commentary on the differences in reactivity between conventional PdII/0 alkene difunctionalization and ones that are mediated by higher oxidation states of palladium. Chapter 3 will present the application of visible light photoredox catalysis towards the degradation of lignin. Lignin is the second most abundant biopolymer on earth and is the only renewable feedstock for aromatic compounds. However, there are no currently implemented technologies that exploit this resource for the purpose of producing renewable fine chemicals. This chapter will discuss our lab’
s first successes in the validation of this concept. Specifically, in the development of a two-stage, chemoselective benzylic alcohol oxidation/photocatalytic reductive C–O bond cleavage reaction. The final chapter will discuss a collaborative project between the Stephenson group and the Pratt group concerning a scalable biomimetic total synthesis of the resveratrol dimers quadrangularin A and pallidol. The beneficial properties of resveratrol are often attributed to its purported ability to act as a radical trapping antioxidant and maintain redox homeostasis within the body. As a result of our synthesis, we were able to provide sufficient material for the rigorous evaluation of its antioxidant activity and challenge this hypothesis.
Advisors/Committee Members: Stephenson, Corey (committee member), Soellner, Matthew Bryan (committee member), Sanford, Melaine S (committee member), Nagorny, Pavel (committee member).
Subjects/Keywords: Photoredox Catalysis; Resveratrol Natural Products; Total Synthesis; Lignin; Biomass Processing; High Valent Palladium Catalysis; Chemistry; Science
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APA (6th Edition):
Matsuura, B. S. (2015). The Development of Transition Metal Catalyzed Reactions for Applications in Complex Molecule Synthesis, Methodological Development and Biomass Processing. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/116626
Chicago Manual of Style (16th Edition):
Matsuura, Bryan Shigeru. “The Development of Transition Metal Catalyzed Reactions for Applications in Complex Molecule Synthesis, Methodological Development and Biomass Processing.” 2015. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/116626.
MLA Handbook (7th Edition):
Matsuura, Bryan Shigeru. “The Development of Transition Metal Catalyzed Reactions for Applications in Complex Molecule Synthesis, Methodological Development and Biomass Processing.” 2015. Web. 07 Mar 2021.
Vancouver:
Matsuura BS. The Development of Transition Metal Catalyzed Reactions for Applications in Complex Molecule Synthesis, Methodological Development and Biomass Processing. [Internet] [Doctoral dissertation]. University of Michigan; 2015. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/116626.
Council of Science Editors:
Matsuura BS. The Development of Transition Metal Catalyzed Reactions for Applications in Complex Molecule Synthesis, Methodological Development and Biomass Processing. [Doctoral Dissertation]. University of Michigan; 2015. Available from: http://hdl.handle.net/2027.42/116626
University of Michigan
4.
Lyons, Thomas W.
Palladium-Catalyzed Cyclopropanation Reactions and Site Selectivity in Palladium-Catalyzed Oxidative Cross-Coupling Reactions.
Degree: PhD, Chemistry, 2011, University of Michigan
URL: http://hdl.handle.net/2027.42/84572
► This thesis describes our efforts at the discovery, optimization, and mechanistic study of two new and fundamentally different Pd–mediated reactions for the construction of bicyclic…
(more)
▼ This thesis describes our efforts at the discovery, optimization, and mechanistic study of two new and fundamentally different Pd–mediated reactions for the construction of bicyclic cyclopropanes as well as biaryl products. Palladium–catalyzed intramolecular carbocyclizations of alkenes and alkynes allow the assembly of complex carbo- and heterocycles from readily available starting materials. We have demonstrated the development of a tandem Pd-catalyzed bis-cyclization/oxidative cleavage sequence with enyne substrates resulting in the formation of cyclopropyl-containing fused heterocycles. Using a PdII catalyst such as Pd(OAc)2, a stoichiometric oxidant such as iodobenzene diacetate, as well as a bidentate ligand such as bipyridine, the assembly of complex bicycles can be achieved with inversion of the starting alkene geometry. Stereochemical and electronic studies indicate the reaction proceeds via a PdII/IV catalytic cycle and has important implications for PdIV reductive elimination processes. This reaction has shown to be tolerant of substituted aryl groups, esters, and tosyl protected amines. Both the synthetic scope and recent mechanistic investigations of this reaction will be discussed in detail.
The second major topic discussed in this thesis is a detailed investigation of the factors controlling site selectivity in the Pd-mediated oxidative coupling of 1,3-disubstituted and 1,2,3-trisubstituted arenes (Aryl–H) with cyclometalating substrates (L~C–H). The influence of both the concentration and the steric/electronic properties of
the quinone promoter are studied in detail. In addition, the effect of steric/electronic modulation of the carboxylate ligand is discussed. Finally, we demonstrate that substitution of the carboxylate for a carbonate X-type ligand leads to a complete reversal in site selectivity for many arene substrates. The origins of these trends in site selectivity are discussed in the context of the mechanism of Pd-catalyzed oxidative cross-coupling.
The final topic of this thesis addresses our efforts at developing a catalytic system for oxidative cross-coupling with new control of site selectivity. A variety of oxidation protocols are described which thus far have failed to produce catalytic turnover.
Advisors/Committee Members: Sanford, Melaine S. (committee member), Matzger, Adam J. (committee member), Savage, Phillip E. (committee member), Wolfe, John P. (committee member).
Subjects/Keywords: Palladium; C-H Activation; Cyclopropanation; Pd(II/IV) Catalysis; Chemistry; Science
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APA ·
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APA (6th Edition):
Lyons, T. W. (2011). Palladium-Catalyzed Cyclopropanation Reactions and Site Selectivity in Palladium-Catalyzed Oxidative Cross-Coupling Reactions. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/84572
Chicago Manual of Style (16th Edition):
Lyons, Thomas W. “Palladium-Catalyzed Cyclopropanation Reactions and Site Selectivity in Palladium-Catalyzed Oxidative Cross-Coupling Reactions.” 2011. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/84572.
MLA Handbook (7th Edition):
Lyons, Thomas W. “Palladium-Catalyzed Cyclopropanation Reactions and Site Selectivity in Palladium-Catalyzed Oxidative Cross-Coupling Reactions.” 2011. Web. 07 Mar 2021.
Vancouver:
Lyons TW. Palladium-Catalyzed Cyclopropanation Reactions and Site Selectivity in Palladium-Catalyzed Oxidative Cross-Coupling Reactions. [Internet] [Doctoral dissertation]. University of Michigan; 2011. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/84572.
Council of Science Editors:
Lyons TW. Palladium-Catalyzed Cyclopropanation Reactions and Site Selectivity in Palladium-Catalyzed Oxidative Cross-Coupling Reactions. [Doctoral Dissertation]. University of Michigan; 2011. Available from: http://hdl.handle.net/2027.42/84572
University of Michigan
5.
Malik, Hasnain A.
Strategies for Regio- and Enantiocontrol in Nickel-Catalyzed Reductive Couplings of Aldehydes and Alkynes.
Degree: PhD, Chemistry, 2011, University of Michigan
URL: http://hdl.handle.net/2027.42/84656
► A highly regioselective nickel-catalyzed reductive couplings of propargyl alcohol derivatives and aldehydes have been developed. Consideration of the interplay of sterics and electronics between reactive…
(more)
▼ A highly regioselective nickel-catalyzed reductive couplings of propargyl alcohol derivatives and aldehydes have been developed. Consideration of the interplay of sterics and electronics between reactive starting materials and the Ni(COD)2/NHC/R3SiH catalyst system allows for a strategy to predictably control regiochemistry in the coupling of propargyl alcohol derivates, aldehydes, and silanes. The derivatization of these products can lead to several otherwise largely inaccessible regioisomers in an indirect but efficient manner.
The ability to reverse alkyne regioselectivity via divergent chemical pathways is known, but to do so with high selectivity across a broad range of substrates is unprecedented. With internal alkynes that lack a strong steric or electronic bias, regioselective couplings to provide either regioisomer selectively are now possible, whereas previously reported protocols were uniformly unselective. With alkynes that possess a strong steric and/or electronic bias, such as aryl alkynes, 1,3-enynes, or terminal alkynes, only a single regioisomer was previously accessible, but our strategy now allows either regioisomer to be selectively obtained. Therefore, the ligand-based control reported herein can override even substantial substrate biases. This study thus provides the first general strategy for controlling regioselectivity in the reductive coupling of aldehydes and alkynes. Regioselectivity reversal for the range of alkynes studied herein rivals that documented for any class of alkyne 1,2-difunctionalization processes.
Studies are ongoing for a general regio- and enantioselective nickel-catalyzed aldehyde-alkyne reductive coupling using chiral N-heterocyclic carbenes.
Advisors/Committee Members: Montgomery, John (committee member), Sanford, Melaine S. (committee member), Sherman, David H. (committee member), Wolfe, John P. (committee member).
Subjects/Keywords: Nickel-Catalyzed Reductive Couplings; Chemistry; Science
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APA (6th Edition):
Malik, H. A. (2011). Strategies for Regio- and Enantiocontrol in Nickel-Catalyzed Reductive Couplings of Aldehydes and Alkynes. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/84656
Chicago Manual of Style (16th Edition):
Malik, Hasnain A. “Strategies for Regio- and Enantiocontrol in Nickel-Catalyzed Reductive Couplings of Aldehydes and Alkynes.” 2011. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/84656.
MLA Handbook (7th Edition):
Malik, Hasnain A. “Strategies for Regio- and Enantiocontrol in Nickel-Catalyzed Reductive Couplings of Aldehydes and Alkynes.” 2011. Web. 07 Mar 2021.
Vancouver:
Malik HA. Strategies for Regio- and Enantiocontrol in Nickel-Catalyzed Reductive Couplings of Aldehydes and Alkynes. [Internet] [Doctoral dissertation]. University of Michigan; 2011. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/84656.
Council of Science Editors:
Malik HA. Strategies for Regio- and Enantiocontrol in Nickel-Catalyzed Reductive Couplings of Aldehydes and Alkynes. [Doctoral Dissertation]. University of Michigan; 2011. Available from: http://hdl.handle.net/2027.42/84656
6.
Nakhla, Josephine S.
Palladium-Catalyzed Carboamination and Carboetherification Reactions for the Synthesis of Heterocycles.
Degree: PhD, Chemistry, 2008, University of Michigan
URL: http://hdl.handle.net/2027.42/60696
► Investigation of the Pd-catalyzed carboamination reaction for the synthesis of substituted piperidines from delta-amino olefins and piperazine heterocycles from amino acid derivatives is described. These…
(more)
▼ Investigation of the Pd-catalyzed carboamination reaction for the synthesis of substituted piperidines from delta-amino olefins and piperazine heterocycles from amino acid derivatives is described. These reactions are believed to proceed via an unprecedented insertion into a Pd–N bond of the key Pd-amido species. These reactions also proceed with excellent levels of 2,6-diastereocontrol (in many cases, >20:1 dr has been observed). The diastereoselectivity of these reactions is also dependent on the protecting group on the cyclizing nitrogen, where more electron rich aryl protecting groups provide more of the cis-diastereomer, whereas less electron rich protecting groups provide slightly lower diastereoselectivity, still favoring the cis-diastereomer. Our stereochemical model differs from related pyrrolidine cyclizations which also provide the cis-diastereomer. We hypothesized that the nitrogen is pyramidalized in the transition state leading to the piperazine and therefore the alpha-substituent can lie in the pseudoequatorial orientation. In addition to 2,6-disubstituted aryl-protected piperazines coupled with aryl halides, we also extended the methodology to include vinyl-halide coupling partners, Boc-protected piperazines, 2,3-disubstituted piperazines, bicyclic piperazines, and benzopiperazines.
The second part of this thesis details intramolecular Pd-catalyzed carboetherification and carboamination reactions for the synthesis of 2-indanyl tetrahydrofurans and 2-indanyl pyrrolidines. These reactions are believed to proceed through an unprecedented macrocyclic insertion into a Pd–O or Pd–N bond to afford products resulting from syn-addition across the olefin. Surprisingly, in the optimization of the carboetherification reactions, we discovered an unprecedented catalyst control on the stereochemical outcome of the reaction. In cases where a monodentate ligand was used in combination with a Pd(0) source, we observed selective formation of the syn-addition diastereomer. When we switched to a catalyst system composed of Pd(0) and a bidentate ligand, we observed formation of the anti-addition diasteromer. We reasoned we were observing a catalyst control of mechanism in the oxypalladation reaction. In the analogous carboamination reactions, we did not observe a complete reversal of diastereoselectivity, but instead erosion of diastereoselectivity. We reasoned this was due to several factors, including the reduced pKa of the aniline versus the alcohol. Further studies to expand the scope of the intramolecular carboetherification and carboamination were also demonstrated.
Advisors/Committee Members: Wolfe, John P. (committee member), Sanford, Melaine S. (committee member), Traynor, John R. (committee member), Vedejs, Edwin (committee member).
Subjects/Keywords: Piperidine; Piperazine; Palladium; Palladium-catalyzed; Tetrahydrofuran; Pyrrolidine; Chemistry; Science
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APA (6th Edition):
Nakhla, J. S. (2008). Palladium-Catalyzed Carboamination and Carboetherification Reactions for the Synthesis of Heterocycles. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/60696
Chicago Manual of Style (16th Edition):
Nakhla, Josephine S. “Palladium-Catalyzed Carboamination and Carboetherification Reactions for the Synthesis of Heterocycles.” 2008. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/60696.
MLA Handbook (7th Edition):
Nakhla, Josephine S. “Palladium-Catalyzed Carboamination and Carboetherification Reactions for the Synthesis of Heterocycles.” 2008. Web. 07 Mar 2021.
Vancouver:
Nakhla JS. Palladium-Catalyzed Carboamination and Carboetherification Reactions for the Synthesis of Heterocycles. [Internet] [Doctoral dissertation]. University of Michigan; 2008. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/60696.
Council of Science Editors:
Nakhla JS. Palladium-Catalyzed Carboamination and Carboetherification Reactions for the Synthesis of Heterocycles. [Doctoral Dissertation]. University of Michigan; 2008. Available from: http://hdl.handle.net/2027.42/60696
7.
Hull, Kami Lee.
Palladium-Catalyzed Oxidative Functionalization of C-H Bonds. Palladium-Catalyzed Oxidative Functionalization of C-H Bonds.
Degree: PhD, Chemistry, 2009, University of Michigan
URL: http://hdl.handle.net/2027.42/62370
► The ability to selectively functionalize complex molecules is an ongoing challenge to chemists; the use of transition-metal catalysts can allow for the direct transformation of…
(more)
▼ The ability to selectively functionalize complex molecules is an ongoing challenge to chemists; the use of transition-metal catalysts can allow for the direct transformation of C–H bonds into a variety of different functional groups. Two significant challenges to this approach are regioselectivity and diversity of functionalization. The approach discussed herein towards achieving regioselectivity has been to use substrates with pendant ligands, which coordinate to a palladium catalyst and direct electrophilic C–H activation to a specific C–H bond. In order to incorporate a variety of functional groups into the substrate, both oxidative functionalization reactions, to form C–OR and C–F bonds, and oxidative coupling reactions, for the formation of a new C–C bond from two C–H bonds have been developed.
We have pioneered a method for the Pd-catalyzed acetoxylation of activated and unactivated, primary and secondary sp3 C–H bonds using pyridine and quinoline directing groups. Additionally, we have demonstrated one of the first metal-catalyzed C–F bond-forming reactions, using commercially available electrophilic fluorine sources as oxidants. This methodology was applied to the formation of a both sp2 and sp3 C–F bonds.
The formation of C–C bonds is an ongoing challenge to organometallic chemists. We felt that in order to maximize atom economy and the overall efficiency, the coupling of two C–H bonds to form a C–C bond would be an ideal process. Using heterocycles as directing groups, select C–H bonds can be coupled under mild reaction conditions. With Oxone as the terminal oxidant, Pd(OAc)2 catalyzes oxidative homodimerization of these heterocyclic substrates to afford homocoupled products in high yield and very high regioselectivity.
The selective formation of unsymmetrical aryl-aryl’ bonds would be a more general process. We have found that palladium, in the presence of benzoquinone and Ag2CO3, can catalyze the cross-coupling of C–H bonds. The first C–H activation is ligand directed followed by a second, undirected C–H activation. The coupled products are formed in high regioselectivity, where the undirected C–H bond activation typically occurs at the least sterically hindered C–H bond.
Advisors/Committee Members: Sanford, Melaine S. (committee member), Matzger, Adam J. (committee member), Schwank, Johannes W. (committee member), Wolfe, John P. (committee member).
Subjects/Keywords: Palladium Catalysis; C-H Activation; Oxidative Coupling; Oxidative Functionalization; Acetoxylation; Fluorination; Chemistry; Science
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APA (6th Edition):
Hull, K. L. (2009). Palladium-Catalyzed Oxidative Functionalization of C-H Bonds. Palladium-Catalyzed Oxidative Functionalization of C-H Bonds. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/62370
Chicago Manual of Style (16th Edition):
Hull, Kami Lee. “Palladium-Catalyzed Oxidative Functionalization of C-H Bonds. Palladium-Catalyzed Oxidative Functionalization of C-H Bonds.” 2009. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/62370.
MLA Handbook (7th Edition):
Hull, Kami Lee. “Palladium-Catalyzed Oxidative Functionalization of C-H Bonds. Palladium-Catalyzed Oxidative Functionalization of C-H Bonds.” 2009. Web. 07 Mar 2021.
Vancouver:
Hull KL. Palladium-Catalyzed Oxidative Functionalization of C-H Bonds. Palladium-Catalyzed Oxidative Functionalization of C-H Bonds. [Internet] [Doctoral dissertation]. University of Michigan; 2009. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/62370.
Council of Science Editors:
Hull KL. Palladium-Catalyzed Oxidative Functionalization of C-H Bonds. Palladium-Catalyzed Oxidative Functionalization of C-H Bonds. [Doctoral Dissertation]. University of Michigan; 2009. Available from: http://hdl.handle.net/2027.42/62370
8.
Remy, Matthew Sean.
Group 10 Methyl Transfer Reactions toward Catalyst Development for Oxidative Oligomerization of Methane.
Degree: PhD, Chemistry, 2011, University of Michigan
URL: http://hdl.handle.net/2027.42/86311
► Abstract Group 10 Methyl Transfer Reactions toward Catalyst Development for Oxidative Oligomerization of Methane by Matthew Sean Remy Chair: Melanie S. Sanford One of the…
(more)
▼ Abstract
Group 10 Methyl Transfer Reactions toward Catalyst Development for Oxidative Oligomerization of Methane
by
Matthew Sean Remy
Chair: Melanie
S.
Sanford
One of the challenges of developing a homogeneous catalyst for oxidative oligomerization of methane (OOM) is promoting a C–C coupling reaction from the product of alkane C–H activation. Heterolytic C–H activation of methane almost exclusively generates a monoalkyl-metal species. In order to make a new C–C bond, it is proposed that a polymethyl intermediate must be generated.
Our studies showed that aryl disproportionation is far more favorable than methyl disproportionation. Careful tuning of ancillary ligands at monomethyl-palladium(II) complexes using density functional theory (DFT) calculations facilitated optimization of thermodynamics for methyl disproportionation. This allowed the first observed disproportionation reaction to form a dimethyl-palladium(II) complex.
Heating dimethyl complex (tBu-bpy)PdII(CH3)2 (tBu-bpy = 4,4-ditertbutyl-2,2-bipyridine) to 100 °C produced a mixture of methane and ethane over 24 h. One-electron oxidants and 1,4-benzoquinone were found to be effective promoters of ethane formation from (tBu-bpy)PdII(CH3)2 at 25 °C. Mechanistic study of one-electron oxidation uncovered an oxidatively-induced methyl transfer reaction which produced ethane from [(tBu-bpy)PdIV(CH3)3(solvent)]+. Subsequently, one-electron oxidation of complexes of the general formula (tBu-bpy)PdII(CH3)X was developed as an effective method for generation of ethane from monomethyl-palladium(II) complexes.
Platinum complexes, (N–N)PtII(CH3)2, similarly undergo one-electron to produce [(N–N)PtIV(CH3)3(solvent)]+. However, these platinum(IV) products are generally stable to reductive elimination of ethane. When the N–N ligand is designed to have steric interactions with axial ligands of platinum(IV), ethane reductive elimination becomes favorable, occurring cleanly over 8.5 hours in acetone and over 1 h in dichloromethane.
This document describes experimental evidence for the generation of polymethyl palladium and platinum complexes from model palladium(II) and platinum(II) products of C–H activation subsequent ethane elimination from the polymethyl complexes.
In an unrelated project, N-insertion into palladium-carbon bond was observed when palladium(II) complexes of bidentate C–N ligands were reacted with an iminoiodinane oxidant. The reaction was proposed to occur through an imido-palladium(IV) intermediate.
Advisors/Committee Members: Sanford, Melaine S. (committee member), Banaszak Holl, Mark M. (committee member), Hollenberg, Paul F. (committee member), Lehnert, Nicolai (committee member).
Subjects/Keywords: One-electron Oxidation of Palladium and Platinum; Methyl Group Transfer; Gas to Liquids; Chemistry; Science
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APA (6th Edition):
Remy, M. S. (2011). Group 10 Methyl Transfer Reactions toward Catalyst Development for Oxidative Oligomerization of Methane. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/86311
Chicago Manual of Style (16th Edition):
Remy, Matthew Sean. “Group 10 Methyl Transfer Reactions toward Catalyst Development for Oxidative Oligomerization of Methane.” 2011. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/86311.
MLA Handbook (7th Edition):
Remy, Matthew Sean. “Group 10 Methyl Transfer Reactions toward Catalyst Development for Oxidative Oligomerization of Methane.” 2011. Web. 07 Mar 2021.
Vancouver:
Remy MS. Group 10 Methyl Transfer Reactions toward Catalyst Development for Oxidative Oligomerization of Methane. [Internet] [Doctoral dissertation]. University of Michigan; 2011. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/86311.
Council of Science Editors:
Remy MS. Group 10 Methyl Transfer Reactions toward Catalyst Development for Oxidative Oligomerization of Methane. [Doctoral Dissertation]. University of Michigan; 2011. Available from: http://hdl.handle.net/2027.42/86311
9.
Fritz, Jonathan A.
Pd-Catalyzed Carboamination Reactions for the Synthesis of Imidazolidin-2-ones and Related Heterocycles.
Degree: PhD, Chemistry, 2009, University of Michigan
URL: http://hdl.handle.net/2027.42/63693
► Imidazolidin-2-ones and related heterocycles have many medicinal and synthetic uses. Progress toward expanding the scope of Pd-catalyzed carboamination to include the synthesis of these classes…
(more)
▼ Imidazolidin-2-ones and related heterocycles have many medicinal and synthetic uses. Progress toward expanding the scope of Pd-catalyzed carboamination to include the synthesis of these classes of heterocycles is demonstrated. 4,4- and 4,5-disubstituted imidazolidin-2-ones were generated in high yield from N-allylureas and aryl bromides. 4,5-disubstituted imidazolidin-2-ones and imidazolidin-2-ones derived from internal olefins were made in moderate to high diastereoselectivity. Vinyl halides were also shown to be effective coupling partners. Orthoganol deprotection of an N1-benzyl N3 p-methoxyphenyl protected imidazolidin-2-ones was achieved. An enantioselective synthesis of imidazolidin-2-ones using chiral ligands or chiral auxiliaries was pursued. Lastly, studies on the Pd-catalyzed carboamination of N-allylguanidines, O-allylcarbamate, homoallylsulfoximines, and N-allylsulfamides are described.
Advisors/Committee Members: Wolfe, John P. (committee member), Montgomery, John (committee member), Sanford, Melaine S. (committee member), Sherman, David H. (committee member).
Subjects/Keywords: Pd-Catalysis; Imidazolidin-2-Ones; Carboamination; Cyclic Ureas; Cyclic Sulfamides; Aminopalladation; Chemistry; Science
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APA (6th Edition):
Fritz, J. A. (2009). Pd-Catalyzed Carboamination Reactions for the Synthesis of Imidazolidin-2-ones and Related Heterocycles. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/63693
Chicago Manual of Style (16th Edition):
Fritz, Jonathan A. “Pd-Catalyzed Carboamination Reactions for the Synthesis of Imidazolidin-2-ones and Related Heterocycles.” 2009. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/63693.
MLA Handbook (7th Edition):
Fritz, Jonathan A. “Pd-Catalyzed Carboamination Reactions for the Synthesis of Imidazolidin-2-ones and Related Heterocycles.” 2009. Web. 07 Mar 2021.
Vancouver:
Fritz JA. Pd-Catalyzed Carboamination Reactions for the Synthesis of Imidazolidin-2-ones and Related Heterocycles. [Internet] [Doctoral dissertation]. University of Michigan; 2009. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/63693.
Council of Science Editors:
Fritz JA. Pd-Catalyzed Carboamination Reactions for the Synthesis of Imidazolidin-2-ones and Related Heterocycles. [Doctoral Dissertation]. University of Michigan; 2009. Available from: http://hdl.handle.net/2027.42/63693
10.
Dickinson, Jacob G.
Reaction Kinetics, Catalyst Development, and Reaction Networks for Hydrothermal Hydrodeoxygenation.
Degree: PhD, Chemical Engineering, 2014, University of Michigan
URL: http://hdl.handle.net/2027.42/108761
► This dissertation examines issues related to producing a hydrocarbon biocrude from wet algal biomass. It first reports on the hydrothermal liquefaction (HTL), a high-temperature (>250…
(more)
▼ This dissertation examines issues related to producing a hydrocarbon biocrude from wet algal biomass. It first reports on the hydrothermal liquefaction (HTL), a high-temperature (>250 °C) and high-pressure (>40 bar) aqueous treatment, of Nannochloropsis sp. to produce a bio-oil. Determining the elemental and molecular composition of the bio-oil, aqueous, gaseous, and solid products produced by HTL at 350 °C revealed how these product compositions are affected by the choice of solvent used to extract the bio-oil. Hexadecane and decane provided the highest gravimetric yields of bio-oil (39 wt% each). Furthermore, quantifying 19 individual molecular components in the bio-oil showed that many of the heteroatoms (N,
S, and O) were present in free fatty acids and heterocyclic molecules.
The removal of oxygen from the bio-oil increases the energy density and stability of the oil, while decreasing the viscosity. Studying the effect of process variables on hydrothermal hydrodeoxygenation (HDO) of benzofuran over Pt/C at 380 °C provided the reaction network and kinetics for benzofuran HDO. The kinetic analysis revealed that benzofuran had an inhibitory effect on the dehydration of ethylphenol to ethylbenzene.
Studying the hydrothermal HDO of o-cresol in a flow reactor at 380 °C showed that Pt/C, Raney Ni, and 10 wt% Raney NiCu were stable under the hydrothermal reaction conditions, but only Pt/C and Raney NiCu were selective for the production liquid hydrocarbons. The Raney NiCu catalyst increased the liquid hydrocarbon yield by a factor of 3.4 when compared with the unmodified Raney Ni.
Raney NiCu catalysts doped with more than 10 wt% Cu showed a significant decrease in gasification activity and an increase in liquid oxygenated products, but no change in the desired liquid hydrocarbons. The addition of acid sites to the NiCu catalysts, either by supporting NiCu on Al2O3 or by calcining the Raney Ni catalyst to convert Al in the catalyst to Al2O3, increased the liquid hydrocarbon yield significantly. In flow reactions, two catalysts, calcined 5% Raney NiCu and 10%, 0.5% NiCu/Al2O3, achieved a high (~70%) and stable yield of liquid hydrocarbons. These catalysts provided the highest known stable yields of liquid hydrocarbons for hydrothermal HDO.
Advisors/Committee Members: Savage, Phillip E. (committee member), Sanford, Melaine S. (committee member), Linic, Suljo (committee member), Thompson Jr, Levi T. (committee member).
Subjects/Keywords: Biofuels; Catalysis; Hydrodeoxygenation; Hydrothermal; Reaction Kinetics; Reaction Networks; Chemical Engineering; Engineering; Science
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APA (6th Edition):
Dickinson, J. G. (2014). Reaction Kinetics, Catalyst Development, and Reaction Networks for Hydrothermal Hydrodeoxygenation. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/108761
Chicago Manual of Style (16th Edition):
Dickinson, Jacob G. “Reaction Kinetics, Catalyst Development, and Reaction Networks for Hydrothermal Hydrodeoxygenation.” 2014. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/108761.
MLA Handbook (7th Edition):
Dickinson, Jacob G. “Reaction Kinetics, Catalyst Development, and Reaction Networks for Hydrothermal Hydrodeoxygenation.” 2014. Web. 07 Mar 2021.
Vancouver:
Dickinson JG. Reaction Kinetics, Catalyst Development, and Reaction Networks for Hydrothermal Hydrodeoxygenation. [Internet] [Doctoral dissertation]. University of Michigan; 2014. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/108761.
Council of Science Editors:
Dickinson JG. Reaction Kinetics, Catalyst Development, and Reaction Networks for Hydrothermal Hydrodeoxygenation. [Doctoral Dissertation]. University of Michigan; 2014. Available from: http://hdl.handle.net/2027.42/108761
11.
Higgs, Andrew T.
Nickel-Mediated Carbon-Heteroatom Bond Formation and Efforts Towards High-Oxidation State Nickel Complexes.
Degree: PhD, Chemistry, 2011, University of Michigan
URL: http://hdl.handle.net/2027.42/84519
► The formation of carbon-heteroatom bonds via reductive elimination from late transition metals is a topic that has recently garnered great interest in the field of…
(more)
▼ The formation of carbon-heteroatom bonds via reductive elimination from late transition metals is a topic that has recently garnered great interest in the field of organometallic chemistry. The
Sanford lab has done a great deal of research in this field, especially with regards to palladium and platinum. Given the high cost and relative rarity of these metals, investigations were extended to nickel.
Ni(phpy)2 (phpy = 2-phenylpyridine) was the initial target due to the success of the analagous PdII(phpy)2 complex at supporting isolable high oxidation state PdIV complexes. The Ni synthesis was accomplished using a metal-assisted deprotonation to install the second phpy ligand onto the metal, following an oxidative addition into the C–Br bond of 2-(2-bromophenyl)pyridine.
NiII(phpy)2 was reacted it with a wide variety of electrophilic oxidants. In all cases, reductive elimination of the C–C homocoupling of the ligands was the major organic product, making further elucidation and identification of the intermediates difficult. The reaction also proceeded too quickly to detect either NiIII or NiIV species spectroscopically, even at low temperatures. Interestingly, however, there were low yields of products resulting from C–X bond reductive elimination.
Van Koten’
s isolation of an organometallic NiIII complex with a nickel-carbon bond and multiple bromide ligands provided an initial point of investigation into the reductive elimination of C–X bonds directly from an isolable NiIII organometallic complex. Under forcing conditions desired product was observed in 33% yield.
Ni(phpy)(Pic)(Br) (Pic = 2-methylepyridine) was reacted with various brominating reagents, which resulted in our desired C–X reductive elimination product (2-(2-bromophneyl)pyridine) being generated in high yields with minimal competing C-C bond formation. Mechanistic investigations suggested that this transformation was possibly taking place via a transient high oxidation state intermediate.
A number of strategies to stabilize a high oxidation state organometallic Ni complex were pursued, including using perhalogenated aryl ligands, trifluoromethyl ligands, and tridentate chelating ligands. Unfortunately, the desired scaffolds were not isolated.
Advisors/Committee Members: Sanford, Melaine S. (committee member), Banaszak Holl, Mark M. (committee member), Carroll, Mary Anne (committee member), Montgomery, John (committee member).
Subjects/Keywords: Nickel; Halogen; Oxidation; Carbon-Halogen Bond Formation; High Oxidation State; Chemistry; Science
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APA (6th Edition):
Higgs, A. T. (2011). Nickel-Mediated Carbon-Heteroatom Bond Formation and Efforts Towards High-Oxidation State Nickel Complexes. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/84519
Chicago Manual of Style (16th Edition):
Higgs, Andrew T. “Nickel-Mediated Carbon-Heteroatom Bond Formation and Efforts Towards High-Oxidation State Nickel Complexes.” 2011. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/84519.
MLA Handbook (7th Edition):
Higgs, Andrew T. “Nickel-Mediated Carbon-Heteroatom Bond Formation and Efforts Towards High-Oxidation State Nickel Complexes.” 2011. Web. 07 Mar 2021.
Vancouver:
Higgs AT. Nickel-Mediated Carbon-Heteroatom Bond Formation and Efforts Towards High-Oxidation State Nickel Complexes. [Internet] [Doctoral dissertation]. University of Michigan; 2011. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/84519.
Council of Science Editors:
Higgs AT. Nickel-Mediated Carbon-Heteroatom Bond Formation and Efforts Towards High-Oxidation State Nickel Complexes. [Doctoral Dissertation]. University of Michigan; 2011. Available from: http://hdl.handle.net/2027.42/84519
12.
Desai, Lopa Vrushank.
Palladium-Catalyzed Functionalization of C-H Bonds and Alkenes.
Degree: PhD, Chemistry, 2008, University of Michigan
URL: http://hdl.handle.net/2027.42/60797
► A highly regio- and chemoselective methodology for the ligand-directed palladium-catalyzed C-H activation/acetoxylation of sp3 C-H bonds was developed. The reaction was found to be general…
(more)
▼ A highly regio- and chemoselective methodology for the ligand-directed palladium-catalyzed C-H activation/acetoxylation of sp3 C-H bonds was developed. The reaction was found to be general with a variety of directing groups such as oxime ethers, isoxazolines and pyridines. In addition, the reaction exhibited high selectivity for the acetoxylation of 1° sp3 C-H bonds.
The ligand directed palladium-catalyzed C-H activation/acetoxylation of sp2 and sp3 C-H bonds was shown to be effective with alternative oxidants such as Oxone and K2S2O8 in place of PhI(OAc)2. The use of these peroxide based oxidants over PhI(OAc)2 is advantageous because they are cheaper and do not release toxic byproducts such as iodobenzene.
A comprehensive investigation to elucidate the factors affecting the C-H activation/acetoxylation by one ligand over another was conducted. It was determined that in the presence of multiple chelating functionalities in a reaction, the substrate bearing the most basic ligand would lead to the predominant product under our reaction conditions. These transformations are believed to proceed via a PdII/IV catalytic cycle. Mechanistic studies implicate that ligand directed palladium mediated C-H activation is the rate-limiting step in these reactions.
Finally, Pd-alkyl intermediates generated via aminopalladation were intercepted using strong oxidants such as PhI(OAc)2 to afford 1,2-difunctionalized products. Under our optimal conditions, the use of alkenes bearing tethered alcohols, acids, or amines led to the formation of substituted tetrahydrofuran rings, lactones, or pyrrolidines.
Advisors/Committee Members: Sanford, Melaine S. (committee member), Gulari, Erdogan (committee member), Vedejs, Edwin (committee member), Wolfe, John P. (committee member).
Subjects/Keywords: Palladium-catalyzed Oxidative Functionalization; Chemistry; Science
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APA (6th Edition):
Desai, L. V. (2008). Palladium-Catalyzed Functionalization of C-H Bonds and Alkenes. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/60797
Chicago Manual of Style (16th Edition):
Desai, Lopa Vrushank. “Palladium-Catalyzed Functionalization of C-H Bonds and Alkenes.” 2008. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/60797.
MLA Handbook (7th Edition):
Desai, Lopa Vrushank. “Palladium-Catalyzed Functionalization of C-H Bonds and Alkenes.” 2008. Web. 07 Mar 2021.
Vancouver:
Desai LV. Palladium-Catalyzed Functionalization of C-H Bonds and Alkenes. [Internet] [Doctoral dissertation]. University of Michigan; 2008. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/60797.
Council of Science Editors:
Desai LV. Palladium-Catalyzed Functionalization of C-H Bonds and Alkenes. [Doctoral Dissertation]. University of Michigan; 2008. Available from: http://hdl.handle.net/2027.42/60797
13.
Geyer, Andrea M.
Development and Investigation of NW(OR)3, NMo(OR)3, and Mo2(OR)6 Complexes for Triple-Bond Metathesis.
Degree: PhD, Chemistry, 2009, University of Michigan
URL: http://hdl.handle.net/2027.42/62253
► The application of alkyne metathesis in the development of polymers, pharmaceuticals, natural products, and many other products has surged. In response, an expansion of current…
(more)
▼ The application of alkyne metathesis in the development of polymers, pharmaceuticals, natural products, and many other products has surged. In response, an expansion of current catalysts and methods to synthesize the catalysts is desired. This work focuses on the systematic design and development of tungsten and molybdenum-based alkylidyne and nitride complexes for triple-bond metathesis.
Nitrile-alkyne cross metathesis (NACM), a new type of metathesis involving the exchange of alkyne and nitrile moieties was developed. NACM activity was found with three tungsten nitride complexes, [N≡W(OCMe2CF3)3]3 (1), N≡W(OCMe¬(CF3)2)3(DME) (2), and [Li(DME)2][N≡W(OCMe(CF3)2)4] (3). Optimization of the NACM conditions including reaction medium, temperature, concentration, and catalyst loading were completed. NACM resulted in a mixture of symmetrical and unsymmetrical alkyne products with 2 favoring the formation of symmetrical alkynes relative to 1. These product ratio differences were accounted for through variances in catalyst resting state during NACM.
The selective formation of symmetrical or unsymmetrical alkynes in high yield can be achieved by altering the reaction conditions. Although 2 exhibits greater NACM activity than 1, broader substrate compatibility is found with 2. Catalyst deactivation was substrate-dependent; conversion to alkylidyne complexes prior to deactivation occurring with some substrates. The utility of NACM was illustrated through the synthesis of large arylene-ethynylene macrocycles.
Methods to readily synthesize alkylidyne species from N≡Mo(OR)3 and Mo2(OR)6 were developed. The irreversible formation of benzylidyne complexes from N≡Mo(OCMe(CF3)2)3 and N≡Mo(OC(CF3)3)3(MeCN) was achieved. The first evidence for the formation of RC≡Mo(OR)3 complexes (OR=OCMe3, OCMe2CF3, and OCMe(CF3)2) through the interaction of Mo2(OR)6 complexes with internal alkynes was discovered. The first example of the reversible formation of alkylidyne and Mo2(OR)6 species (OR=OCMe3, OCMe2CF3) was also achieved.
Extension of the formation of molybdenum alkylidyne complexes from nitride complexes that contain OCMe¬3 and OCMe2CF3 ligands was achieved in situ in the presence of Lewis acids. Attempted isolation of alkylidyne complexes formed in situ was unsuccessful due to decomposition of the formed alkylidyne species in the presence of the Lewis acid. Several simple Lewis acids were found to increase the rate of alkyne metathesis with N≡Mo(OR)3 and Mo2(OR)6 complexes (OR= OCMe3, OCMe2CF3, and OCMe(CF3)2).
Advisors/Committee Members: Johnson, Marc J. (committee member), Montgomery, John (committee member), Sanford, Melaine S. (committee member), Schwank, Johannes W. (committee member).
Subjects/Keywords: Alkyne Metathesis; Nitrile-alkyne Cross-metathesis; Molybdenum Alkylidyne; Tungsten Alkylidyne; Mo2(OR)6; Chemistry; Science
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APA ·
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APA (6th Edition):
Geyer, A. M. (2009). Development and Investigation of NW(OR)3, NMo(OR)3, and Mo2(OR)6 Complexes for Triple-Bond Metathesis. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/62253
Chicago Manual of Style (16th Edition):
Geyer, Andrea M. “Development and Investigation of NW(OR)3, NMo(OR)3, and Mo2(OR)6 Complexes for Triple-Bond Metathesis.” 2009. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/62253.
MLA Handbook (7th Edition):
Geyer, Andrea M. “Development and Investigation of NW(OR)3, NMo(OR)3, and Mo2(OR)6 Complexes for Triple-Bond Metathesis.” 2009. Web. 07 Mar 2021.
Vancouver:
Geyer AM. Development and Investigation of NW(OR)3, NMo(OR)3, and Mo2(OR)6 Complexes for Triple-Bond Metathesis. [Internet] [Doctoral dissertation]. University of Michigan; 2009. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/62253.
Council of Science Editors:
Geyer AM. Development and Investigation of NW(OR)3, NMo(OR)3, and Mo2(OR)6 Complexes for Triple-Bond Metathesis. [Doctoral Dissertation]. University of Michigan; 2009. Available from: http://hdl.handle.net/2027.42/62253
14.
Cychosz, Katie A.
Microporous Coordination Polymers As Selective Adsorbents For Complex Matrices.
Degree: PhD, Chemistry, 2010, University of Michigan
URL: http://hdl.handle.net/2027.42/77735
► Crystalline microporous coordination polymers (MCPs) are ordered, porous materials that have recently seen increasing attention in the literature. Whereas gas phase separations using MCPs have…
(more)
▼ Crystalline microporous coordination polymers (MCPs) are ordered, porous materials that have recently seen increasing attention in the literature. Whereas gas phase separations using MCPs have been extensively studied and reviewed, studies on applications in the liquid phase, particularly from complex matrices, have lagged behind. In this thesis, MCPs have been applied to adsorption from diesel and water.
The utility of MCPs for the adsorption of large organosulfur compounds (benzothiophene, dibenzothiophene, 4,6-dimethyldibenzothiophene) found as pollutant precursors in fuels was demonstrated. Large capacities were obtained, particularly for 4,6-dimethyldibenzothiophene, the compound most difficult to remove using current industrial techniques. It was determined that the size/shape of the pores in the MCP, rather than surface area or pore volume, is the most important factor controlling adsorption capacity. This was confirmed by studying the supramolecular isomers
University of
Michigan Crystalline Material (UMCM)-152 and UMCM-153 which exhibited different adsorption behaviors. Electron-deficient MCPs were also tested and higher adsorption capacities were observed for the most electron-deficient structure.
MCPs were demonstrated to be efficient adsorbents for the removal of the organosulfur compounds dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (DMDBT) from model fuel and diesel fuel in packed bed breakthrough experiments. Unlike activated carbons, where selectivity has been a problem, MCPs selectively adsorb the organosulfur compounds over similar components of diesel. Complete regeneration using toluene at modest temperatures was achieved. The attainment of high selectivities and capacities, particularly for the adsorption of the difficult to remove refractory compounds, in a reversible sorbent indicates that fuel desulfurization may be an important application for MCPs.
Finally, the water stability of a variety of MCPs was studied using powder X-ray diffraction. It was determined that the stability of the MCP is related to the metal cluster present in the structure with trinuclear chromium clusters more stable than copper paddlewheel clusters which are more stable than basic zinc acetate clusters. Matériaux de l’Institut Lavoisier (MIL)-100 was found to be completely water stable and was used to adsorb the pharmaceuticals furosemide and sulfasalazine from water with large uptakes at low concentrations, indicating that the adsorption of wastewater contaminants may be a feasible application for these materials.
Advisors/Committee Members: Matzger, Adam J. (committee member), Montgomery, John (committee member), Sanford, Melaine S. (committee member), Thompson, Jr., Levi T. (committee member).
Subjects/Keywords: Microporous Coordination Polymer; Adsorption; Desulfurization; Water Stability; Metal-organic Framework; Breakthrough Curve; Chemistry; Science
…the supramolecular isomers
University of Michigan Crystalline Material (UMCM)-152… …PIZA), and University of Michigan Crystalline Material (UMCM).
These materials…
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APA (6th Edition):
Cychosz, K. A. (2010). Microporous Coordination Polymers As Selective Adsorbents For Complex Matrices. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/77735
Chicago Manual of Style (16th Edition):
Cychosz, Katie A. “Microporous Coordination Polymers As Selective Adsorbents For Complex Matrices.” 2010. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/77735.
MLA Handbook (7th Edition):
Cychosz, Katie A. “Microporous Coordination Polymers As Selective Adsorbents For Complex Matrices.” 2010. Web. 07 Mar 2021.
Vancouver:
Cychosz KA. Microporous Coordination Polymers As Selective Adsorbents For Complex Matrices. [Internet] [Doctoral dissertation]. University of Michigan; 2010. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/77735.
Council of Science Editors:
Cychosz KA. Microporous Coordination Polymers As Selective Adsorbents For Complex Matrices. [Doctoral Dissertation]. University of Michigan; 2010. Available from: http://hdl.handle.net/2027.42/77735
15.
Walker, Randon H.
Silylene and Germylene Activation of Alkane, Ether and Amine C-H Bonds Mediated by an Aryl Halide. Observation of an Aryl Halide Kinetic Isotope Effect for the C-H Activation Reaction.
Degree: PhD, Chemistry, 2009, University of Michigan
URL: http://hdl.handle.net/2027.42/64636
► Two new types reactions capable of activation the C-H bond α to nitrogen are reported. The silylene [(CH)2tBu2N2]Si (1) was found to activate the weakest…
(more)
▼ Two new types reactions capable of activation the C-H bond α to nitrogen are reported. The silylene [(CH)2tBu2N2]Si (1) was found to activate the weakest C-H bond of alkanes, ethers or amines when combined with an equivalent of an aryl halide. A competing reaction pathway to the C-H activation is oxidative addition of the aryl halide to 1, dilution techniques were used for reducing the percentage of oxidative addition product formed. Additionally, the germeylene [TMS2HC]2Ge (21) was also observed to C-H activate amines when combined with an aryl halide. Amine substrate with C(sp3)-H bonds α and β to the amine nitrogen atom demonstrate different reactivity with 1/Ph-I and 21/Ph-I. For example, reacting Et3N with 1/Ph-I forms the single C-H activation product [(CH)2tBu2N2]Si(I)[CH(CH3)NEt2] (7), a small percentage of [(CH)2tBu2N2]Si(I)(Ph) (2) and [(CH)2tBu2N2]Si(H)(NEt2) (8). In contrast, reacting Et3N with 21/Ph-I results in quantitative formation of [TMS2HC]2Ge(I)(H) (27). Independent synthesis of 8, or 27, was achieved by reacting 1, or 21, in Et3N with [Et3NH]I, implying in situ formation of [Et3NH]I.
Deuterium labeled compounds were used for gaining a better understanding of the rate-determining step. The silylene C-H activation reaction of Et2O was found to have a KIE of 5.7 ± 0.1, a magnitude consistent with the C-H bond breaking at or before the rate-determining step. Additionally, the C-H activation of Et2O with 1/Ph-X or 21/Ph-X resulted in a KIE for the protons of the aryl halide. The KIEs of the aryl group range from a low of 1.1 ± 0.1 for 1/4-C6H4DI to high of 1.7 ± 0.1 for 21/C6D5Br. The aryl KIEs are consistent with the Ar-X bond breaking at or before the rate-determining step.
Advisors/Committee Members: Banaszak Holl, Mark M. (committee member), Coppola, Brian P. (committee member), Krajcik, Joseph S (committee member), Sanford, Melaine S. (committee member), Wolfe, John P. (committee member).
Subjects/Keywords: Silylenes; Germylenes; Kinetic Isotope Effect; C-H Bond Activation; Chemistry; Science
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APA (6th Edition):
Walker, R. H. (2009). Silylene and Germylene Activation of Alkane, Ether and Amine C-H Bonds Mediated by an Aryl Halide. Observation of an Aryl Halide Kinetic Isotope Effect for the C-H Activation Reaction. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/64636
Chicago Manual of Style (16th Edition):
Walker, Randon H. “Silylene and Germylene Activation of Alkane, Ether and Amine C-H Bonds Mediated by an Aryl Halide. Observation of an Aryl Halide Kinetic Isotope Effect for the C-H Activation Reaction.” 2009. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/64636.
MLA Handbook (7th Edition):
Walker, Randon H. “Silylene and Germylene Activation of Alkane, Ether and Amine C-H Bonds Mediated by an Aryl Halide. Observation of an Aryl Halide Kinetic Isotope Effect for the C-H Activation Reaction.” 2009. Web. 07 Mar 2021.
Vancouver:
Walker RH. Silylene and Germylene Activation of Alkane, Ether and Amine C-H Bonds Mediated by an Aryl Halide. Observation of an Aryl Halide Kinetic Isotope Effect for the C-H Activation Reaction. [Internet] [Doctoral dissertation]. University of Michigan; 2009. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/64636.
Council of Science Editors:
Walker RH. Silylene and Germylene Activation of Alkane, Ether and Amine C-H Bonds Mediated by an Aryl Halide. Observation of an Aryl Halide Kinetic Isotope Effect for the C-H Activation Reaction. [Doctoral Dissertation]. University of Michigan; 2009. Available from: http://hdl.handle.net/2027.42/64636
University of Michigan
16.
Buhrlage, Sara J.
Small Molecule Transcriptional Activation Domains.
Degree: PhD, Chemistry, 2008, University of Michigan
URL: http://hdl.handle.net/2027.42/61622
► Transcriptional activators are essential for high fidelity transcription, responsible for seeking out particular genes and up-regulating them to precise levels in a signal responsive fashion.…
(more)
▼ Transcriptional activators are essential for high fidelity transcription, responsible for seeking out particular genes and up-regulating them to precise levels in a signal responsive fashion. Indeed the altered transcription patterns observed in disease states can often be attributed to malfunctioning and/or misregulated transcriptional activators. Thus, molecules that can reconstitute the function of transcriptional activators, artificial transcription activators, are highly desirable commodities as mechanistic tools and transcription-targeted therapeutics. Transcriptional activators control the specificity and extent of gene upregulation through two domains: the DNA binding domain (DBD) is responsible for the former and the transcriptional activation domain (TAD) dictates the level of gene expression. It has proven quite challenging to identify TAD replacements with functional properties comparable to the natural system despite their likely advantages in terms of stability, delivery, and and/or immunogenic properties. This is
likely due to the many open questions surrounding how natural transcriptional activation domains function.
To address the need for the development and characterization of small molecule TADs we have employed a combination of organic chemistry, NMR spectroscopy, and biological evaluations to a class of isoxazolidines that functionally mimic natural TADs. We prepared five stereochemically pure isoxazolidine isomers, each of which contained identical functional groups (benzyl, isobutyl and hydroxyl) arranged in different positions around the isoxazolidine ring. All of these amphipathic isoxazolidines functioned as TADs in a cell-free assay, revealing that analogous to endogenous TADs, a particular positioning of functional groups is not required for transcription function. Similar functional trends were observed in a cellular assay. We further demonstrated that the small molecule TADs interact with at least a subset of the same coactivator proteins as do natural TADs. In particular, interaction with the KIX domain of Creb Binding Protein is correlated with transcription function, although binding interactions with Tra1, Med15 and Med23 are also observed. These molecules are thus anticipated to be an excellent starting point for the design of more potent small molecule regulators of transcription.
Advisors/Committee Members: Mapp, Anna K. (committee member), Al-Hashimi, Hashim (committee member), Neubig, Richard Robert (committee member), Sanford, Melaine S. (committee member).
Subjects/Keywords: Transcriptional Activation Domains; Chemistry; Science
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APA (6th Edition):
Buhrlage, S. J. (2008). Small Molecule Transcriptional Activation Domains. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/61622
Chicago Manual of Style (16th Edition):
Buhrlage, Sara J. “Small Molecule Transcriptional Activation Domains.” 2008. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/61622.
MLA Handbook (7th Edition):
Buhrlage, Sara J. “Small Molecule Transcriptional Activation Domains.” 2008. Web. 07 Mar 2021.
Vancouver:
Buhrlage SJ. Small Molecule Transcriptional Activation Domains. [Internet] [Doctoral dissertation]. University of Michigan; 2008. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/61622.
Council of Science Editors:
Buhrlage SJ. Small Molecule Transcriptional Activation Domains. [Doctoral Dissertation]. University of Michigan; 2008. Available from: http://hdl.handle.net/2027.42/61622
University of Michigan
17.
Whitfield, Salena Renice.
New Oxidation Reactions of Palladium and Platinum: Synthetic and Mechanistic Investigations.
Degree: PhD, Chemistry, 2008, University of Michigan
URL: http://hdl.handle.net/2027.42/60697
► Organic and inorganic oxidation reactions involving the metals palladium and platinum were developed. Palladium-catalyzed carbon-hydrogen (C-H) functionalization via acetoxylation was shown to proceed efficiently using…
(more)
▼ Organic and inorganic oxidation reactions involving the metals palladium and platinum were developed. Palladium-catalyzed carbon-hydrogen (C-H) functionalization via acetoxylation was shown to proceed efficiently using an oxidant immobilized on a solid support. The polymer oxidant has several advantages over a traditional monomer oxidant, including, but not limited to, cost, atom economy, and recyclability. Both sp2 and sp3 C-H bonds of small molecules were transformed using this methodology.
Palladium was also employed in stoichiometric oxidation reactions. Oxidation of PdII(phpy)2 (phpy = 2-phenylpyridine) using the electrophilic chlorinating reagents, PhICl2 and NCS, accessed the elusive high oxidation state of PdIV. Novel complexes were identified and characterized, incorporating 2 chlorine ligands or 1 chlorine ligand and the succinimide ligand. Both complexes were shown to undergo facile reductive elimination to produce C-Cl, C-C, and even C-N coupled organic products. Other PdIV complexes were synthesized, examining the outcome of organic reductive elimination from a metal complex with two different ligands, acetate and chlorine. Initial results demonstrate that solvent and ligand position strongly influence the observed organic products.
Platinum complexes were also oxidized by the afore mentioned electrophilic chlorinating reagents. Using conditions from the palladium system, oxidation with PhICl2 afforded similar PtIV dichloride products, while oxidation with NCS produced a PtIII complex as the major product. The reaction conditions were found to vary the observed ratios of products in the NCS oxidations. These factors were examined in an effort to propose a mechanism to explain formation of all of the species.
Finally, platinum complexes were oxidized by a series of traditional and non-traditional oxidants to access PtIII and PtIV halogen and carboxylate complexes. Traditional oxidants included Br2 and I2, while non-traditional oxidants included XeF2, PhI(OAc)2 and PhI(C2F3O2)2. All of the compounds formed were stable to ambient conditions. Organic reductive elimination products were not observed in any of the thermolysis experiments. Upon heating the PtIV complexes either experienced no change or isomerized to an alternate geometry.
Advisors/Committee Members: Sanford, Melaine S. (committee member), Becker, Udo (committee member), Matzger, Adam J. (committee member), Wolfe, John P. (committee member).
Subjects/Keywords: Palladium and Platinum Oxidation; Chemistry; Science
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APA (6th Edition):
Whitfield, S. R. (2008). New Oxidation Reactions of Palladium and Platinum: Synthetic and Mechanistic Investigations. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/60697
Chicago Manual of Style (16th Edition):
Whitfield, Salena Renice. “New Oxidation Reactions of Palladium and Platinum: Synthetic and Mechanistic Investigations.” 2008. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/60697.
MLA Handbook (7th Edition):
Whitfield, Salena Renice. “New Oxidation Reactions of Palladium and Platinum: Synthetic and Mechanistic Investigations.” 2008. Web. 07 Mar 2021.
Vancouver:
Whitfield SR. New Oxidation Reactions of Palladium and Platinum: Synthetic and Mechanistic Investigations. [Internet] [Doctoral dissertation]. University of Michigan; 2008. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/60697.
Council of Science Editors:
Whitfield SR. New Oxidation Reactions of Palladium and Platinum: Synthetic and Mechanistic Investigations. [Doctoral Dissertation]. University of Michigan; 2008. Available from: http://hdl.handle.net/2027.42/60697
University of Michigan
18.
Giampietro, Natalie C.
Development of Reactions for the Stereoselective Synthesis of Heterocycles and Enantioselective Synthesis of Diols and Amino-Alcohols.
Degree: PhD, Chemistry, 2010, University of Michigan
URL: http://hdl.handle.net/2027.42/77680
► Part One of this thesis describes the synthesis of heterocycles containing two heteroatoms via palladium-catalyzed carboamination and carboetherification reactions. The development of a new stereoselective…
(more)
▼ Part One of this thesis describes the synthesis of heterocycles containing two heteroatoms via palladium-catalyzed carboamination and carboetherification reactions. The development of a new stereoselective synthesis of cis- and trans-disubstituted pyrazolidines from N-butenyl hydrazine derivatives is described. The products are generated with good to excellent diastereoselectivity and chemical yield and can be transformed to synthetically useful pyrazolines or 1,3-diamines via oxidation or reduction. Importantly, these experiments also demonstrate that allylic strain interactions can be manipulated through a simple substrate modification (N2-protection vs. no N2-protection) to allow for control of relative stereochemistry in Pd-catalyzed reactions. Upon completion of this work, we became interested in whether manipulation of allyic strain as a means to control product stereochemistry would be applicable in the synthesis of other heterocycles. Thus, application of this concept in isoxazolidine synthesis is described. A new method for pyrrolidinone synthesis via Pd-catalyzed carboamination of γ,δ-unsaturated amides with aryl or alkenyl bromides is also described. The pyrrolidinone
products are accessed in good to excellent yields, and have the potential to be useful precursors in a variety of other interesting transformations.
Part Two of this thesis describes new methods for the enantioselective synthesis of diols and amino-alcohols. The research presented in Chapters VI-VII describe development of a tandem reaction sequence towards a new method for the formation of enantioenriched α-alkyl-α,β-dihydroxy esters (Wittig rearrangement/aldol reactions) and α-alkyl-α-hydroxy-β-amino esters (Wittig rearrangement/Mannich reactions) involving reaction of chiral glycolate esters with various electrophilic coupling partners. The asymmetric Wittig/Aldol reactions are the first examples of tandem reactions involving enolate [1,2]-Wittig rearrangements that afford nonracemic products, and are also the first asymmetric aldol reactions of α-alkyl-α-hydroxy ester enolates that generate unprotected diol products with both high syn:anti selectivity and high ee. In addition, these results have led to the development of the first asymmetric Mannich reactions of ester enolates that afford both syn- and anti-α-alkyl-α-hydroxy-β-amino esters with both high dr and ee. These are also the first examples of asymmetric Mannich reactions that proceed via tetrasubstituted enolboronate intermediates.
Advisors/Committee Members: Wolfe, John P. (committee member), Montgomery, John (committee member), Sanford, Melaine S. (committee member), Soellner, Matthew Bryan (committee member).
Subjects/Keywords: Stereoselective Synthesis of Heterocycles Via Carboamination and Carboetherification Reactions; Enantioselective Synthesis of Diols and Amino-Alcohols Via Asymmetric Wittig/Aldol and Wittig/Mannich Reactions; Chemistry; Science
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APA ·
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MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
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APA (6th Edition):
Giampietro, N. C. (2010). Development of Reactions for the Stereoselective Synthesis of Heterocycles and Enantioselective Synthesis of Diols and Amino-Alcohols. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/77680
Chicago Manual of Style (16th Edition):
Giampietro, Natalie C. “Development of Reactions for the Stereoselective Synthesis of Heterocycles and Enantioselective Synthesis of Diols and Amino-Alcohols.” 2010. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/77680.
MLA Handbook (7th Edition):
Giampietro, Natalie C. “Development of Reactions for the Stereoselective Synthesis of Heterocycles and Enantioselective Synthesis of Diols and Amino-Alcohols.” 2010. Web. 07 Mar 2021.
Vancouver:
Giampietro NC. Development of Reactions for the Stereoselective Synthesis of Heterocycles and Enantioselective Synthesis of Diols and Amino-Alcohols. [Internet] [Doctoral dissertation]. University of Michigan; 2010. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/77680.
Council of Science Editors:
Giampietro NC. Development of Reactions for the Stereoselective Synthesis of Heterocycles and Enantioselective Synthesis of Diols and Amino-Alcohols. [Doctoral Dissertation]. University of Michigan; 2010. Available from: http://hdl.handle.net/2027.42/77680
University of Michigan
19.
Beaudoin Bertrand, Myra.
Methodology Development for the Stereoselective Synthesis of Protected Pyrrolidines and à-Alkyl-à,á-Dihydroxy Esters.
Degree: PhD, Chemistry, 2008, University of Michigan
URL: http://hdl.handle.net/2027.42/60805
► This thesis describes the development of methods for the stereoselective synthesis of protected pyrrolidines and -alkyl-,-dihydroxy esters. The method for the synthesis of protected pyrrolidines…
(more)
▼ This thesis describes the development of methods for the stereoselective synthesis of protected pyrrolidines and -alkyl-,-dihydroxy esters. The method for the synthesis of protected pyrrolidines is a palladium-catalyzed carboamination of protected -amino alkenes with aryl halides, and accomplishes the formation of both a carbon-nitrogen and carbon-carbon bond and up to two stereocenters in a single step with up to >20:1 diastereoselectivity. The scope of this transformation is described in detail, along with a refinement of reaction conditions which improve the functional group tolerance, and broaden the range of substrates that can be effectively transformed. A discussion of the diastereoselectivity obtained in the formation of disubstituted protected pyrrolidines is also presented. This methodology has been applied to the stereoselective synthesis of antifungal and antitumor agents preussin and 3-epi-preussin, along with new preussin analogs that differ in their aromatic ring substitution. Studies towards the synthesis of pyrrolidine alkaloid anisomycin are also described.
During the course of studies on Pd-catalyzed carboamination reactions that employ mild bases, we discovered a tandem directed carbopalladation/C–H bond functionalization that afforded cyclopentane-fused benzocyclobutene molecules. The scope of this new reaction is discussed along with a mechanistic hypothesis on the origin of these products.
The second part of this thesis describes a new method for the synthesis of -alkyl-,-dihydroxy esters. This transformation involves a tandem Wittig rearrangement-aldolreaction of methyl O-benzyl and methyl O-allyl glycolate esters, and was discovered during our work towards the synthesis of anisomycin. The reaction affords -alkyl-,-dihydroxy esters in one step with >20:1 diastereoselectivity. The scope, limitations and mechanism of this new reaction are also discussed.
Advisors/Committee Members: Wolfe, John P. (committee member), Sanford, Melaine S. (committee member), Sherman, David H. (committee member), Vedejs, Edwin (committee member).
Subjects/Keywords: Pyrrolidine; Wittig Rearrangement; Aldol; Palladium; Carboamination; Chemistry; Science
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Export
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APA (6th Edition):
Beaudoin Bertrand, M. (2008). Methodology Development for the Stereoselective Synthesis of Protected Pyrrolidines and à-Alkyl-à,á-Dihydroxy Esters. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/60805
Chicago Manual of Style (16th Edition):
Beaudoin Bertrand, Myra. “Methodology Development for the Stereoselective Synthesis of Protected Pyrrolidines and à-Alkyl-à,á-Dihydroxy Esters.” 2008. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/60805.
MLA Handbook (7th Edition):
Beaudoin Bertrand, Myra. “Methodology Development for the Stereoselective Synthesis of Protected Pyrrolidines and à-Alkyl-à,á-Dihydroxy Esters.” 2008. Web. 07 Mar 2021.
Vancouver:
Beaudoin Bertrand M. Methodology Development for the Stereoselective Synthesis of Protected Pyrrolidines and à-Alkyl-à,á-Dihydroxy Esters. [Internet] [Doctoral dissertation]. University of Michigan; 2008. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/60805.
Council of Science Editors:
Beaudoin Bertrand M. Methodology Development for the Stereoselective Synthesis of Protected Pyrrolidines and à-Alkyl-à,á-Dihydroxy Esters. [Doctoral Dissertation]. University of Michigan; 2008. Available from: http://hdl.handle.net/2027.42/60805
University of Michigan
20.
Kalyani, Dipannita.
Site Selectivity in Palladium-Catalyzed Oxidative Functionalization Reactions.
Degree: PhD, Chemistry, 2008, University of Michigan
URL: http://hdl.handle.net/2027.42/61588
► The development of transformations for selective and functional group tolerant methods for the direct functionalization of C–H bonds is an important challenge in organic chemistry.…
(more)
▼ The development of transformations for selective and functional group tolerant methods for the direct functionalization of C–H bonds is an important challenge in organic chemistry. Recent work in our group has shown that Pd(OAc)2 in conjunction with PhI(OAc)2 serves as an efficient catalyst for ligand-directed palladium-catalyzed C–H activation/acetoxylation reactions. These reactions are believed to proceed via a PdII/IV catalytic cycle.
In order to expand the scope of these oxygenation reactions we sought to explore whether high and predictable levels of site selectivity could be achieved for the functionalization of meta-substituted arenes. In general, our results show that the palladium-catalyzed C–H activation/acetoxylation of meta-substituted arenes occurs preferentially at the less congested position.
Additionally, we desired to install other functionalities such as halogen and aryl groups in the final products using electrophilic halogenating and arylating reagents as terminal oxidants. A detailed exploration of palladium-catalyzed chelate-directed halogenation of arenes using N-halosuccinimides as terminal oxidants has been conducted. Additionally, we have shown that diaryl iodonium salts can be used as oxidants for site selective C–H activation/arylation reactions in the presence of Pd(OAc)2 as the catalyst. Preliminary results suggest that the mechanism of this reaction involves a PdII/PdIV catalytic cycle, which is of interest because nearly all palladium mediated C–C bond forming reactions proceed via a Pd0/PdII cycle.
Finally, we have applied the insights gained from the aforementioned oxidation reactions toward the oxidative halogenation of PdII-alkyl complexes generated via olefin insertion into Pd-aryl bonds to form 1,2-arylhalogenated products. Interestingly, the isomeric 1,1-arylhalogenated products could also be obtained in high selectivity just by tuning the reaction conditions.
In all, this thesis describes a variety of site selective palladium-catalyzed oxidative functionalization reactions. These include palladium-catalyzed chelate-directed C–H activation/C–X (X = C, O, Cl, Br, I) bond formation and the palladium-catalyzed difunctionalization of olefins. The PdII/IV catalytic cycle proposed for many of these transformations has allowed for bond formations (e.g., carbon-halogen) that previously proved challenging via traditional Pd0/II catalytic cycles. The generality, high selectivity, and functional group tolerance of these reactions make them attractive for the functionalization, late stage derivatization, and the synthesis of complex biologically active molecules.
Advisors/Committee Members: Sanford, Melaine S. (committee member), Matzger, Adam J. (committee member), Savage, Phillip E. (committee member), Wolfe, John P. (committee member).
Subjects/Keywords: Palladium-Catalyzed Oxidative Functionalization; Science
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APA ·
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MLA ·
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APA (6th Edition):
Kalyani, D. (2008). Site Selectivity in Palladium-Catalyzed Oxidative Functionalization Reactions. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/61588
Chicago Manual of Style (16th Edition):
Kalyani, Dipannita. “Site Selectivity in Palladium-Catalyzed Oxidative Functionalization Reactions.” 2008. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/61588.
MLA Handbook (7th Edition):
Kalyani, Dipannita. “Site Selectivity in Palladium-Catalyzed Oxidative Functionalization Reactions.” 2008. Web. 07 Mar 2021.
Vancouver:
Kalyani D. Site Selectivity in Palladium-Catalyzed Oxidative Functionalization Reactions. [Internet] [Doctoral dissertation]. University of Michigan; 2008. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/61588.
Council of Science Editors:
Kalyani D. Site Selectivity in Palladium-Catalyzed Oxidative Functionalization Reactions. [Doctoral Dissertation]. University of Michigan; 2008. Available from: http://hdl.handle.net/2027.42/61588
University of Michigan
21.
Herath-Mudiyansela, Ananda H. B.
Development of Nickel-Catalyzed Cycloaddition and Coupling Reactions.
Degree: PhD, Chemistry, 2008, University of Michigan
URL: http://hdl.handle.net/2027.42/60689
► Nickel-catalyzed carbon-carbon bond-forming reactions provide a potentially useful strategy to generate a variety of organic compounds efficiently,regioselectively, chemoselectively, and stereoselectively. The versatility of these types…
(more)
▼ Nickel-catalyzed carbon-carbon bond-forming reactions provide a potentially useful strategy to generate a variety of organic compounds efficiently,regioselectively, chemoselectively, and stereoselectively. The versatility of these
types of reactions makes them a powerful tool in organic synthesis. This dissertation mainly focuses on methodology development involving nickel
catalysis. In this work, a number of highly selective reactions of readily available
precursors, such as alkynes, enals and enones were developed.
In one application, a novel, nickel-catalyzed [3+2] cycloaddition of enals
and alkynes was explored. This reaction provides a diastereoselective and
chemoselective entry to five-membered rings, which are a common structural
motif in many architecturally complex and biologically active natural
products. In another application, a novel, nickel-catalyzed intermolecular reductive
coupling of enones and alkynes was developed. The key feature of this reaction
is the chemoselective coupling of two potential Michael acceptors such as
enones and alkynoates. The direct participation of alkynes as an alternative to
preparing and handling sensitive vinyl cuprate reagents provides potentially
significant improvements in accessing γ,δ-unsaturated ketones.
An intriguing, nickel-catalyzed, intermolecular reductive coupling of enals
and alkynes has also been developed. The unique features of this reaction are
the construction of geometrically pure Z-enol silanes and high functional group
tolerance. The direct participation of enals, alkynes and silanes as an alternative
to existing methods provides potentially significant improvements in accessing
enol silanes. Additionally, this reaction provides direct evidence for the catalytic
involvement of a seven-membered oxametallacycle intermediate.
A novel, nickel-catalyzed intermolecular three-component coupling of
aldehydes, alkynes, and enones has been developed. This new process involves
an internal redox mechanism and proceeds in the absence of reducing agents
that have previously been required in related nickel-catalyzed couplings. The
high extent of chemoselectivity is unusual, particularly for aldehyde, enone,
alkyne couplings that involve three different π-components. Together, these new methods provide access to interesting chemical
scaffolds and greatly expand the versatility of nickel-catalyzed reactions.
Advisors/Committee Members: Montgomery, John (committee member), Gestwicki, Jason E. (committee member), Sanford, Melaine S. (committee member), Vedejs, Edwin (committee member).
Subjects/Keywords: DEVELOPMENT OF NICKEL-CATALYZED CYCLOADDITION AND; Chemistry; Science
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APA ·
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MLA ·
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APA (6th Edition):
Herath-Mudiyansela, A. H. B. (2008). Development of Nickel-Catalyzed Cycloaddition and Coupling Reactions. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/60689
Chicago Manual of Style (16th Edition):
Herath-Mudiyansela, Ananda H B. “Development of Nickel-Catalyzed Cycloaddition and Coupling Reactions.” 2008. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/60689.
MLA Handbook (7th Edition):
Herath-Mudiyansela, Ananda H B. “Development of Nickel-Catalyzed Cycloaddition and Coupling Reactions.” 2008. Web. 07 Mar 2021.
Vancouver:
Herath-Mudiyansela AHB. Development of Nickel-Catalyzed Cycloaddition and Coupling Reactions. [Internet] [Doctoral dissertation]. University of Michigan; 2008. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/60689.
Council of Science Editors:
Herath-Mudiyansela AHB. Development of Nickel-Catalyzed Cycloaddition and Coupling Reactions. [Doctoral Dissertation]. University of Michigan; 2008. Available from: http://hdl.handle.net/2027.42/60689
University of Michigan
22.
Casey, Ryan J.
Design and Synthesis of Non-Peptidic Transcription Factors.-.
Degree: PhD, Chemistry, 2010, University of Michigan
URL: http://hdl.handle.net/2027.42/75818
► Transcription is important for the determination of cellular phenotype through the regulation of gene expression and its mis-regulation can lead to abnormal cell function. Transcriptional…
(more)
▼ Transcription is important for the determination of cellular phenotype through the
regulation of gene expression and its mis-regulation can lead to abnormal cell function.
Transcriptional activators are essential for high fidelity transcription, responsible for
seeking out particular genes and up-regulating them to precise levels in a signalresponsive
fashion. Molecules that can reconstitute the function of transcriptional
activators, artificial transcription activators, are highly desirable commodities as
mechanistic tools and transcription-based therapeutics. Transcriptional activators control
the specificity and extent of gene upregulation through two domains: the DNA binding
domain (DBD) confers specific binding to DNA and the transcriptional activation domain
(TAD) dictates the level of gene expression. Many questions surrounding how natural
transcriptional activation domains function has hindered the development of TAD
replacements despite their likely advantages in terms of stability, delivery, and and/or
immunogenic properties.
To address the need for the development and characterization of small molecule
xv
TADs we have employed a combination of organic chemistry and biological evaluations
to produce a class of isoxazolidines that functionally mimic natural TADs. We identified
the first small molecule, an amphipathic isoxazolidine, that reconstitutes transcription in
living cell culture. Additionally, the amphipathic isoxazoldine alone can competitively
inhibit the DNA localized-isoxazolidine, indicating that it is the isoxazolidine moiety that
makes contacts with the transcriptional machinery that are important for activation. Many
different peptide sequences can function as activators and we hypothesized this feature
would translate to other suitably functionalized small molecules. Indeed, other
isoxazolidine and non-isoxazolidine TADs activated transcription in cell culture. With an
array of small molecule TADs, we designed activator artificial transcription factors and
tested them for activation in cell culture.
Advisors/Committee Members: Mapp, Anna (committee member), Gestwicki, Jason E. (committee member), Montgomery, John (committee member), Sanford, Melaine S. (committee member).
Subjects/Keywords: Chemical Biology; Organic Chemistry; Transcription; Biological Chemistry; Chemistry; Science
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APA (6th Edition):
Casey, R. J. (2010). Design and Synthesis of Non-Peptidic Transcription Factors.-. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/75818
Chicago Manual of Style (16th Edition):
Casey, Ryan J. “Design and Synthesis of Non-Peptidic Transcription Factors.-.” 2010. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/75818.
MLA Handbook (7th Edition):
Casey, Ryan J. “Design and Synthesis of Non-Peptidic Transcription Factors.-.” 2010. Web. 07 Mar 2021.
Vancouver:
Casey RJ. Design and Synthesis of Non-Peptidic Transcription Factors.-. [Internet] [Doctoral dissertation]. University of Michigan; 2010. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/75818.
Council of Science Editors:
Casey RJ. Design and Synthesis of Non-Peptidic Transcription Factors.-. [Doctoral Dissertation]. University of Michigan; 2010. Available from: http://hdl.handle.net/2027.42/75818
University of Michigan
23.
Wiedner, Eric Scott.
Triple-Bond Metathesis with Group 6 Nitrido Complexes: The Importance of Ligand Identity and the Development of XXX Pincer Ligands.
Degree: PhD, Chemistry, 2009, University of Michigan
URL: http://hdl.handle.net/2027.42/64651
► Triple-bond metathesis is a useful methodology for the synthesis of new organic functionalities. Alkyne cross metathesis (ACM) has been employed in the synthesis of materials…
(more)
▼ Triple-bond metathesis is a useful methodology for the synthesis of new organic functionalities. Alkyne cross metathesis (ACM) has been employed in the synthesis of materials with unusual optical properties and in the construction of biologically relevant molecules. Installation of an alkyne functionality into a substrate is often more challenging than introduction of a nitrile group. Therefore nitrile-alkyne cross metathesis
(NACM) is desirable to allow for greater flexibility in the construction of carbon-carbon
triple bonds. Using NW(OC(CF3)2Me)3(DME) (1) as a catalyst, the utility of NACM is demonstrated in the synthesis of an arylene-ethynylene macrocycle via a shorter route than possible through ACM. Catalyst 1 was found to be sensitive to both polar and protic functional groups. Molybdenum NACM catalysts were designed in order to overcome the limited functional group tolerance of 1. The activation barrier for metalacycle formation is larger for Mo than W, therefore elevated temperatures are required to effect a complete NACM cycle with Mo complexes. Using the thermally robust triphenylsiloxide ligand, NMo(OSiPh3)3 (2) successfully catalyzed NACM at 185 °C. The triphenylsiloxide ligand was found to have a proper electron donor strength, as other Mo complexes did not catalyze NACM under similar conditions. Trianionic (XXX) pincer ligands were designed in order to lower the activation barrier required for Mo-catalyzed NACM. The compound 1,3-bis(4,5-(3,5-dimethylphenyl)-1H-imidazol-2-yl)benzene (3) was synthesized as an XXX pincer ligand precursor. While 3 proved challenging to install onto Mo complexes as desired, 3 was facilely activated by Zr(NMe2)4. Subsequent investigations of the Zr-XXX complexes revealed an unusual charge-switching feature in which the XXX ligand could be converted into a monoanionic (LXL) ligand. The XXX-LXL transformation could be
effected through methylation, borylation, and silylation, with reversibility being possible through silyl group cleavage. Computational studies revealed differing electron donating
strengths of the XXX and LXL ligands, suggesting that the pincer ligand charge could be used to alter the reactivity patterns of metal complexes. In order to realize the goal of using an XXX ligand for Mo catalysts, 1,8-bis(4,5-bis(3,5-dimethylphenyl)-1H-imidazol-2-yl)-3,6-di-tert-butyl-9H-carbazole was synthesized as a new XXX ligand precursor. Future studies will explore the application of the new ligand in catalysis of NACM.
Advisors/Committee Members: Johnson, Marc J. (committee member), Sanford, Melaine S. (committee member), Banaszak Holl, Mark M. (committee member), Laine, Richard M. (committee member).
Subjects/Keywords: Nitrile Alkyne Cross Metathesis; Triple Bond Metathesis; Trianionic Pincer Ligand; Charge Switching Ligand; Molybdenum Nitride; Triphenylsiloxide; Chemistry; Science
Record Details
Similar Records
Cite
Share »
Record Details
Similar Records
Cite
« Share
❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Wiedner, E. S. (2009). Triple-Bond Metathesis with Group 6 Nitrido Complexes: The Importance of Ligand Identity and the Development of XXX Pincer Ligands. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/64651
Chicago Manual of Style (16th Edition):
Wiedner, Eric Scott. “Triple-Bond Metathesis with Group 6 Nitrido Complexes: The Importance of Ligand Identity and the Development of XXX Pincer Ligands.” 2009. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021.
http://hdl.handle.net/2027.42/64651.
MLA Handbook (7th Edition):
Wiedner, Eric Scott. “Triple-Bond Metathesis with Group 6 Nitrido Complexes: The Importance of Ligand Identity and the Development of XXX Pincer Ligands.” 2009. Web. 07 Mar 2021.
Vancouver:
Wiedner ES. Triple-Bond Metathesis with Group 6 Nitrido Complexes: The Importance of Ligand Identity and the Development of XXX Pincer Ligands. [Internet] [Doctoral dissertation]. University of Michigan; 2009. [cited 2021 Mar 07].
Available from: http://hdl.handle.net/2027.42/64651.
Council of Science Editors:
Wiedner ES. Triple-Bond Metathesis with Group 6 Nitrido Complexes: The Importance of Ligand Identity and the Development of XXX Pincer Ligands. [Doctoral Dissertation]. University of Michigan; 2009. Available from: http://hdl.handle.net/2027.42/64651
. 
Open Access Theses and Dissertations
