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°.
Additional indexing
Item Type: | Journal Article, refereed, original work |
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Communities & Collections: | 07 Faculty of Science > Department of Chemistry |
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Dewey Decimal Classification: | 540 Chemistry |
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Language: | German |
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Date: | 1993 |
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Deposited On: | 26 Dec 2013 09:51 |
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Last Modified: | 24 Sep 2019 19:53 |
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Publisher: | Wiley-Blackwell |
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ISSN: | 0018-019X |
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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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OA Status: | Closed |
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Project Information: | - : FunderSNSF
- : Grant ID
- : Project TitleSchweizerischer Nationalfonds zur Förderung der wissenschaftlichen Forschung
- : Funder
- : Grant ID
- : Project TitleF. Hoffmann-La Roche AG, Basel
- : Funder
- : Grant ID
- : Project TitleRektor der Universität Lodz (Uni-Lodz-Forschungsprogramm)
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