PROCESS FOR THE PREPARATION OF AZETIDINONE DERIVATIVES

摘要

7.beta.-amino-3-hydroxy-1-carba(1-dethia)-3-cephem-4-carboxylic acid esters of Formula (I): (I) wherein R1 is C1-C6 alkyl; a phenyl group wherein a and a' independently are hydrogen, C1-C4 alkyl, C1-C4 alkoxy or halogen; a group represented by the formula wherein Z is O or S, m is 0 or 1, and a and a' have the same meanings as defined above; or R1 is R1'O wherein R1' represents C1-C4 alkyl, C5-C7 cycloalkyl, benzyl, nitrobenzyl, methoxybenzyl, or halobenzyl; and R2 is a carboxy-protecting group, are prepared by cyclization of cis-3-(substituted amino)-1-(2-substituted 2oxoethyl)-4-azetidin-2-one propanoic acid esters of Formula (II): (II) wherein R1 and R2 are as defined above and R3 is a leaving roup, employing a non-nucleophilic strong base. The 7.beta.-amino-3-hydroxy-1-carba(1-dethia)-3-cephem-4-carboxylic acid esters are useful chiral intermediates to .beta.-lactam antibiotics.