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Synthese von (Methylthio)penam-Derivaten durch Keten-Addition an 4,5-Dihydro-5-(methylthio)-1,3-thiazole


Jenny, Christjohannes; Prewo, Roland; Bieri, Jost H; Heimgartner, Heinz (1986). Synthese von (Methylthio)penam-Derivaten durch Keten-Addition an 4,5-Dihydro-5-(methylthio)-1,3-thiazole. Helvetica Chimica Acta, 69(6):1424-1434.

Abstract

The 4,5-dihydro-5-(methyIthio)-2-phenyl-1,3-thiazoles 3a and 3b, easily prepared from the corresponding 1,3-thiazol-5(4H)-thiones and MeLi, react with dichloroacetyl chloride (5a) and acidoacetyl chloride (5b) in the presence of Et3N to give (methylthio)penam derivatives 6 (Table 1). The reaction mechanism is either a [2+2] cycloaddition of in situ generated ketene or a two-step reaction (Scheme 2). The structure of 6f has been confirmed by X-ray crystallography (Fig. 2). The relative configuration of 6a-e follow from comparison of their 1H-NMR spectra with those of 6f (Fig. 1). The 6-azidopenams 6d and 6f have been reduced to aminopenams 8a and 8b, respectively. Acylation of 8a with phenacetyl chloride yields 9 (Scheme 4 ).

Abstract

The 4,5-dihydro-5-(methyIthio)-2-phenyl-1,3-thiazoles 3a and 3b, easily prepared from the corresponding 1,3-thiazol-5(4H)-thiones and MeLi, react with dichloroacetyl chloride (5a) and acidoacetyl chloride (5b) in the presence of Et3N to give (methylthio)penam derivatives 6 (Table 1). The reaction mechanism is either a [2+2] cycloaddition of in situ generated ketene or a two-step reaction (Scheme 2). The structure of 6f has been confirmed by X-ray crystallography (Fig. 2). The relative configuration of 6a-e follow from comparison of their 1H-NMR spectra with those of 6f (Fig. 1). The 6-azidopenams 6d and 6f have been reduced to aminopenams 8a and 8b, respectively. Acylation of 8a with phenacetyl chloride yields 9 (Scheme 4 ).

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Additional indexing

Other titles:Synthesis of (Methylthio)penam Derivatives via Keten Addition onto 4,5-Dihydro-5-(methyIthio)-1,3-thiazoles
Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:German
Date:1986
Deposited On:03 Jun 2014 07:04
Last Modified:05 Apr 2016 17:54
Publisher:Wiley-Blackwell
ISSN:0018-019X
Funders:Schweizerischer Nationalfonds zur Förderung der wissenschaftlichen Forschung, F. Hoffmann-La Roche & Co. AG, Basel
Publisher DOI:https://doi.org/10.1002/hlca.19860690615

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