Azetidinone intermediates for cephalosporin analogs

摘要

Intermediates of the following formula are useful for the synthesis of 1-oxacephalosporins. Their preparation from penicillins and the transformation process to make 1-oxacephalosporins are disclosed. The compounds are of the formula: <IMAGE> wherein A is amino or a selected acylamino; COB is carboxy or a selected protected-carboxy; X is halogen or the group OR in which R is a group represented by following formulas: CH2CCH, CH2CCNu, CH2CHCH2, <IMAGE> +TR <IMAGE> wherein Nu is a selected nucleophilic group; R1 is a group of the following formula: <IMAGE> in which Hal is halogen or alkylsulfonyloxy and R2 is alkyl or aryl; and Y is hydrogen or methoxy; with the proviso that when R is propargyl or 2-oxopropyl and R1 is <IMAGE> A is in the 3 alpha -configuration and Y is 3 beta -hydrogen or A is in the 3 beta -configuration and Y is 3 alpha -methoxy.