New 1-oxa-1-dethia-cephalosporin derivatives.

摘要

Disclosed are new 2-alkyl-1-oxa-1-dethiacephalosporin derivatives of the general formula:
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and pharmaceutically acceptable salts or esters thereof, wherein R represents a group of the formula:
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in which R1 is a 2-thienyl or 3-thienyl group and R2 is a hydrogen atom or a carboxyl group, or R-represents a group of the formula:
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in which R3 is a hydrogen atom, a lower alkyl or carboxyllower alkyl group; R4 represents a hydrogen atom or a methoxy group, R5 represents a lower alkyl group; R6 represents