HIGHLY ASYMMETRIC PUMMERER-TYPE CYCLIZATION OF CHIRAL, NON-RACEMIC BETA-AMIDO SULFOXIDES

The first highly asymmetric Pummerer-type cyclization of chiral non-racemic beta-amido sulfoxides to enantiomerically enriched beta-lactams (80-85% ee) is described. S- and R-Sulfoxides (S-2a-d and R-2a-c) were treated with O-methyl-O-tert-butyldimethylsilyl ketene acetal 1 in the presence of a cata...

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Published inJ. Chem. Soc., Perkin Trans. 1 no. 19; pp. 2405 - 2410
Main Authors KITA, Y, SHIBATA, N, KAWANO, N, TOHJO, T, FUJIMORI, C, MATSUMOTO, K, FUJITA, S
Format Journal Article
LanguageEnglish
Published CAMBRIDGE Royal Soc Chemistry 1995
Subjects
Chemistry
Chemistry, Organic
Physical Sciences
Science & Technology
BIOMIMETIC SYNTHESIS
ENANTIOSELECTIVE SYNTHESIS
SILYLATED KETENE ACETALS
EFFICIENT SYNTHESIS
CHEMISTRY
CARBAPENEM ANTIBIOTICS
2-(ALKYLTHIO)PENEM-3-CARBOXYLIC ACIDS
ACETIC-ANHYDRIDE
STEREOSELECTIVE SYNTHESIS
LACTAM ANTIBIOTICS
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Summary:The first highly asymmetric Pummerer-type cyclization of chiral non-racemic beta-amido sulfoxides to enantiomerically enriched beta-lactams (80-85% ee) is described. S- and R-Sulfoxides (S-2a-d and R-2a-c) were treated with O-methyl-O-tert-butyldimethylsilyl ketene acetal 1 in the presence of a catalytic amount of zinc chloride in methylene dichloride to give predominantly the corresponding 4R- and 4S-beta-lactams (R-3a-d and S-3a-c) in more than 80% ee. These results show that the stereoinduction is governed by the absolute configuration of the sulfoxides. Optically pure R- and S-3c were readily obtained by simple recrystallization in about 60% yield, The usefulness of the chiral, non-racemic 4-tolylsulfanyl-beta-lactams 3a-d has been shown by their conversion into the key intermediate 11 for the optically pure carbapenem antibiotic, (+)-PS-5.
ISSN:1472-7781
0300-922X
1364-5463
DOI:10.1039/p19950002405