Solid and solution phase synthesis of α-keto amides via azetidinone ring-opening: Application to the synthesis of poststatin

Abstract

3,3-Diethoxy-N-sulfonyl and carbamoyl azetidin-2-ones undergo efficient ring-opening reaction with various amine nucleophiles. Subsequent acid hydrolysis of the ketal moiety generated α-keto amides in excellent overall yields. The naturally occurring serine protease inhibitor poststatin was synthesized using this ring-opening reaction as the key step.