Process for the preparation of 2-halomethyl-penems and their use for the preparation of antibacterial penems.

摘要

Process for the preparation of 2-halomethyl-penems (I) comprising (a) reacting an acetoxy-(protected hydroxyethyl)-2-azetidinone (III) with a 2-halothioacetic acid to form a 3-haloacetylthioazetidinone (V), (b) reacting (V) with oxalyl chloride to give an intermediate (VII), acylated on the beta-lactamic nitrogen, and (c) cyclizing (VII) in the presence of an organic phosphate or phosphonite to produce the corresponding 2-halomethyl-penem (I).