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Umsetzung von 1,3-Thiazol-5(4H)-thionen mit Diazomethan


Kägi, Martin; Linden, Anthony; Heimgartner, Heinz; Mloston, Grzegorz (1993). Umsetzung von 1,3-Thiazol-5(4H)-thionen mit Diazomethan. Helvetica Chimica Acta, 76:1715-1728.

Abstract

Reaction of 1,3-Thiazole-5(4H)-thiones and Diazomethane. Reaction of 4,4-dimethyl-1,3-thiazol-5(4H)-thiones1 with diazomethane in Et2O at -78° or 0° leads to a mixture of the corresponding 1,4-dithiane 10, 1,3-dithiole 11, thiirane 12, 4,5-dihydro-5-methylidene-1,3-thiazole 13, and 1,3-thiazol-5(4H)-one 14 (Scheme 3). The structures of 10a, 11a , and 11b have been established by X-ray crystallography. The formation of the products can be explained via an intermediate thiocarbonyl ylide of type E (Scheme 4), generated by the 1,3-dipolar cycloaddition of diazomethane with the exocyclic C=S bond of 1 and elimination of N2. Head-to-head dimerization of E yields 10, 1,3-dipolar cycloaddition of E and 1 gives the 'Schönberg product' 11, and cyclization of E leads to 12, which undergoes a desulfurization to give 13. The thiazolone 14 is formed by hydrolysis of E. The similarity of the ratio of the products at -78° and at O° shows that, in contrast to the reaction of 1 and 2-diazopropane, the elimination of N2 in the primary cycloadduct already occurs at -78°.

Abstract

Reaction of 1,3-Thiazole-5(4H)-thiones and Diazomethane. Reaction of 4,4-dimethyl-1,3-thiazol-5(4H)-thiones1 with diazomethane in Et2O at -78° or 0° leads to a mixture of the corresponding 1,4-dithiane 10, 1,3-dithiole 11, thiirane 12, 4,5-dihydro-5-methylidene-1,3-thiazole 13, and 1,3-thiazol-5(4H)-one 14 (Scheme 3). The structures of 10a, 11a , and 11b have been established by X-ray crystallography. The formation of the products can be explained via an intermediate thiocarbonyl ylide of type E (Scheme 4), generated by the 1,3-dipolar cycloaddition of diazomethane with the exocyclic C=S bond of 1 and elimination of N2. Head-to-head dimerization of E yields 10, 1,3-dipolar cycloaddition of E and 1 gives the 'Schönberg product' 11, and cyclization of E leads to 12, which undergoes a desulfurization to give 13. The thiazolone 14 is formed by hydrolysis of E. The similarity of the ratio of the products at -78° and at O° shows that, in contrast to the reaction of 1 and 2-diazopropane, the elimination of N2 in the primary cycloadduct already occurs at -78°.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:German
Date:1993
Deposited On:26 Dec 2013 09:51
Last Modified:05 Apr 2016 17:19
Publisher:Wiley-Blackwell
ISSN:0018-019X
Funders:Schweizerischer Nationalfonds zur Förderung der wissenschaftlichen Forschung, F. Hoffmann-La Roche AG, Basel, Rektor der Universität Lodz (Uni-Lodz-Forschungsprogramm)

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