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A new synthetic approach to 5-dethia-4-methyl-5-oxacephems

✍ Scribed by Zbigniew Kałuża; Arkadiusz Kazimierski; Krzysztof Lewandowski; Kinga Suwińska; Beata Szczȩsna; Marek Chmielewski

Book ID
104205553
Publisher
Elsevier Science
Year
2003
Tongue
French
Weight
301 KB
Volume
59
Category
Article
ISSN
0040-4020

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✦ Synopsis

Starting from (L)-ethyl lactate and 4-vinyloxy-azetidin-2-one the diastereomeric (4S,6R)-and (4S,6S)-4-methyl-5-oxa-3methylene and 3-oxo-cephams were obtained. The formation of the cepham skeleton proceeds with a diastereomeric excess up to 80%, depending on catalyst and reaction conditions. For comparison, the corresponding racemic cephams lacking a methyl at C-4 or with a gemdimethyl group at C-4 were synthesized.

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