4-substituted azetidinones as precursors to 2-substituted-3-carboxy carbapenem antibiotics and a method of producing them

摘要

New 4-substituted azetidinones having the formulae I and II: <IMAGE> I <IMAGE> II wherein X is oxygen, sulfur or a moiety of the formula NR6 where R1, R2, R3, R4, R5 and R6 are defined hereafter, which are intermediates for the preparation of carbapenem and carbacephem antibacterials and processes for producing such antibacterials through the utilization of an acid mediated ring closure reaction.