Novel N1-C4 β-lactam bond breakage.: Synthesis of enantiopure α-alkoxy-γ-keto acid derivatives

Addition reaction of 2-(trimethylsilyl)thiazole (TMST) to cis- or trans-4-formyl-beta-lactams gave enantiopure alpha-alkoxy-gamma-keto acid derivatives via a novel N1-C4 bond breakage of the beta-lactam nucleus. This is the first time that the cleavage of the N1-C4 bond on the beta-lactam nucleus has been shown to occur in 2-azetidinones lacking an aryl moiety at C4.