4-SUBSTITUTED BUTYRIC ACID DERIVATIVES,PROCESSES FOR THE PREPARATION THEREOF AND ANTIBACTERIAL,PHARMACEUTICAL AND VETERINARY PREPARATIONS PREPARED THEREFROM

摘要

Useful intermediates, 7 alpha -acylamino-3-(oxo or exomethylene)-1-dethia-1-oxacepham-4 alpha -carboxylates, are produced by the intramolecular carbenoid insertion of a 2-diazo-3-(oxo or exomethylene)-4-(3 alpha -acylamino-2-oxoazetidin-4 beta -yl)oxybutyrate prepared in several steps from the corresponding oxazolinoazetidinone and diketone.