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1. Roelfsema, W.A. Aminering van hydroxyderivaten van halogeenazahetarenen.

Degree: 1972, Landbouwhogeschool Wageningen

In this thesis an introductory investigation is described on the reactivity of hydroxy derivatives of halogenopyridines and a bromohydroxyquinoline towards strong bases. It is a sequel to earlier work on the effect of substituents present in the nucleus of halogenopyridines on the course of aminations of these substances (chapter 1). Halogenohydroxy compounds were reacted with potassium amide or lithium piperidide, whereupon products were isolated, identified and determined quantitatively. Mechanisms were suggested interpreting the results obtained. Details about amination procedures and analyses of reaction mixtures are given in chapter 2. When various halogenohydroxypyridines are reacted with potassium amide in liquid ammonia at -33°C, substitutions, cine-substitutions and ring contractions occur. It was shown that part of the bromohydroxypyridines are aminated according to the elimination-addition (EA)mechanism via hydroxy-3,4-didehydropyridines as intermediates. The addition of ammonia to the triple bond in the intermediate is directed by the hydroxy group. Depending on this effect one or two aminohydroxy compounds are formed. Thus, cine-substitution takes place exclusively in the transformation of 3-bromo-5-hydroxypyridine via 5-hydroxy-3,4-didehydropyridine into 4-amino-5-hydroxypyridine. The amination of 4-bromo-2-hydroxypyridine follows a more complicated pattern, presumably involving two isomeric hydroxydidehydropyridines. It leads to the formation of a mixture of 3- and 4- amino-2-hydroxypyridine (chapter 3). From both 2- and 3-bromo-4-hydroxypyridine, 2-amino-4-hydroxypyridine is formed. These reactions can be explained, assuming divergent AE-processes (chapter 4). The amination of 2-bromo-6-hydroxypyridine takes place without rearrangement. Continued investigation is required to establish whether this process follows the AE pathway. Remarkable results were met when studying the amination of 2-chloro-3-hydroxypyridine, 2-bromo-3-hydroxypyridine and three derivatives of the latter. These substances change into pyrrole derivatives. In contrast to the reaction of 3-amino-2-bromopyridine with potassium amide yielding 3-cyanopyrrole, the halogeno-hydroxypyridines are converted into pyrrole carbonamides, in which the substituent occupies the 2-position. A 3-substituted pyrrole derivative was obtained from our substrates however, when lithium piperidide was used as a reagent. Together with this product (i.e. pyrrole-3-carbopiperidide), 3-hydroxy-2-piperidinopyridine is obtained. The mechanism of the reactions of 2-halogeno-3- hydroxypyridines and those of the corresponding amino and methyl compounds are discussed (chapter 5). Ring contraction takes place too in the amination with potassium amide, of 4-bromo-3-hydroxyquinoline i.e. a derivative of 4-bromo-3-hydroxypyridine from which no hydrogen bromide can be abstracted leading to the formation of a 4,5-didehydro compound. In this reaction oxindole is the product. Thus, along with the ring-fission a fragment of… Advisors/Committee Members: H.J. den Hertog.

Subjects/Keywords: pyridines; piperidinen; derivaten; chinolinen; chinoline; indolen; chemische reacties; aminen; pyrrool; Organische chemie; pyridines; piperidines; derivatives; quinolines; quinoline; indoles; chemical reactions; amines; pyrrole; Organic Chemistry

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APA (6th Edition):

Roelfsema, W. A. (1972). Aminering van hydroxyderivaten van halogeenazahetarenen. (Doctoral Dissertation). Landbouwhogeschool Wageningen. Retrieved from http://library.wur.nl/WebQuery/wurpubs/421729 ; urn:nbn:nl:ui:32-421729 ; urn:nbn:nl:ui:32-421729 ; http://library.wur.nl/WebQuery/wurpubs/421729

Chicago Manual of Style (16th Edition):

Roelfsema, W A. “Aminering van hydroxyderivaten van halogeenazahetarenen.” 1972. Doctoral Dissertation, Landbouwhogeschool Wageningen. Accessed January 18, 2020. http://library.wur.nl/WebQuery/wurpubs/421729 ; urn:nbn:nl:ui:32-421729 ; urn:nbn:nl:ui:32-421729 ; http://library.wur.nl/WebQuery/wurpubs/421729.

MLA Handbook (7th Edition):

Roelfsema, W A. “Aminering van hydroxyderivaten van halogeenazahetarenen.” 1972. Web. 18 Jan 2020.

Vancouver:

Roelfsema WA. Aminering van hydroxyderivaten van halogeenazahetarenen. [Internet] [Doctoral dissertation]. Landbouwhogeschool Wageningen; 1972. [cited 2020 Jan 18]. Available from: http://library.wur.nl/WebQuery/wurpubs/421729 ; urn:nbn:nl:ui:32-421729 ; urn:nbn:nl:ui:32-421729 ; http://library.wur.nl/WebQuery/wurpubs/421729.

Council of Science Editors:

Roelfsema WA. Aminering van hydroxyderivaten van halogeenazahetarenen. [Doctoral Dissertation]. Landbouwhogeschool Wageningen; 1972. Available from: http://library.wur.nl/WebQuery/wurpubs/421729 ; urn:nbn:nl:ui:32-421729 ; urn:nbn:nl:ui:32-421729 ; http://library.wur.nl/WebQuery/wurpubs/421729

2. Jespers, A.B.K. Mode of action of the phenylpyrrole fungicide fenpiclonil in Fusarium sulphureum.

Degree: 1994, Agricultural University

In the last few decades, plant disease control has become heavily dependent on fungicides. Most modem fungicides were discovered by random synthesis and empirical optimization of lead structures. In general, these fungicides have specific modes of action and meet modem enviromnental criteria. A disadvantage of modem fungicides is the potency of plant pathogens to acquire fungicide resistance. This phenomenon urges the agrochemical industry to search for chemicals with new modes of action. Natural products often have unique modes of action and can be used as lead structures in chemical synthesis programmes. One natural lead structure is the antifungal antibiotic pyrrolnitrin, produced by several Pseudomonas species. Its use in an optimization programme of CIBA-GEIGY A.G., Basel, Switzerland, led to the development of the highly active phenylpyrrole fungicides fenpiclonil (CGA 142705) and fludioxonil (CGA 173506). The elucidation of the mode of action of fenpiclonil is the topic of this thesis. Fenpiclonil is toxic to representatives of Ascomycetes, Basidiomycetes and Deuteromycetes. Its effect on several physiological processes was studied using the fungus Fusarium sulphureum as a sensitive target organism. The EC 50 of fenpiclonil to radial growth on PDA and mycelial growth in Czapek Dox liquid medium is 0.5 and 4 μM, respectively. Fenpiclonil accumulates to a high level in mycelium of F. sulphureum and in artificial liposomes. The accumulation appears to be the result of a physico-chemical partitioning of the fungicide over lipids in mycelium and the medium. Accumulation is reversible as the fungicide is readily released from mycelium by washing with water. The fungus does not metabolize fenpiclonil upon incubation for 24 hours. At its EC 50 (4 μM), feripiclonil does not immediately affect oxygen consumption, nuclear division, and DNA-, RNA-, protein-, chitin-, ergosterol- and (phospho)lipid biosynthesis. However, accumulation of amino acids and sugars is instantaneously inhibited at concentrations ranging from 4.2- 42 μM), The reduction in accumulation is accompanied by an increased accumulation of the membrane potential probe tetraphenylphosphonium(TPP +) bromide (TPP +) and a marginal change of the proton gradient probe propionic acid. This suggests that the biochemical mechanism of action of fenpiclonil may be related to membrane dependent transport processes. The increased accumulation of TPP +is probably the result of changes of potentials over membranes of various cell compartments rather than from plasma membrane hyperpolarization. The fungicide neither influences membrane fluidity in artificial liposomes nor amino acid accumulation in bacterial vesicles. Thus, accumulation of the fungicide does not aspecifically effect functioning of various types of membranes. At its EC 15 (0.4 μM), fenpiclonil selectively inhibits accumulation and incorporation of various monosaccharides into macromolecules of <em>F.… Advisors/Committee Members: P.J.G.M. de Wit, M.A. de Waard.

Subjects/Keywords: gewasbescherming; pesticiden; pesticidenwerking; ongediertedodende eigenschappen; fungiciden; derivaten; deuteromycotina; pyrrool; tuberculariaceae; Fungiciden, bactericiden; Toxiciteit van bestrijdingsmiddelen; plant protection; pesticides; pesticidal action; pesticidal properties; fungicides; derivatives; deuteromycotina; pyrrole; tuberculariaceae; Fungicides, Bactericides; Toxicity of Pesticides

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Jespers, A. B. K. (1994). Mode of action of the phenylpyrrole fungicide fenpiclonil in Fusarium sulphureum. (Doctoral Dissertation). Agricultural University. Retrieved from http://library.wur.nl/WebQuery/wurpubs/24307 ; urn:nbn:nl:ui:32-24307 ; urn:nbn:nl:ui:32-24307 ; http://library.wur.nl/WebQuery/wurpubs/24307

Chicago Manual of Style (16th Edition):

Jespers, A B K. “Mode of action of the phenylpyrrole fungicide fenpiclonil in Fusarium sulphureum.” 1994. Doctoral Dissertation, Agricultural University. Accessed January 18, 2020. http://library.wur.nl/WebQuery/wurpubs/24307 ; urn:nbn:nl:ui:32-24307 ; urn:nbn:nl:ui:32-24307 ; http://library.wur.nl/WebQuery/wurpubs/24307.

MLA Handbook (7th Edition):

Jespers, A B K. “Mode of action of the phenylpyrrole fungicide fenpiclonil in Fusarium sulphureum.” 1994. Web. 18 Jan 2020.

Vancouver:

Jespers ABK. Mode of action of the phenylpyrrole fungicide fenpiclonil in Fusarium sulphureum. [Internet] [Doctoral dissertation]. Agricultural University; 1994. [cited 2020 Jan 18]. Available from: http://library.wur.nl/WebQuery/wurpubs/24307 ; urn:nbn:nl:ui:32-24307 ; urn:nbn:nl:ui:32-24307 ; http://library.wur.nl/WebQuery/wurpubs/24307.

Council of Science Editors:

Jespers ABK. Mode of action of the phenylpyrrole fungicide fenpiclonil in Fusarium sulphureum. [Doctoral Dissertation]. Agricultural University; 1994. Available from: http://library.wur.nl/WebQuery/wurpubs/24307 ; urn:nbn:nl:ui:32-24307 ; urn:nbn:nl:ui:32-24307 ; http://library.wur.nl/WebQuery/wurpubs/24307

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