The Indium‐Mediated Selective Introduction of Allenyl and Propargyl Groups at the C4‐Position of 2‐Azetidinones and the AuCl₃‐Catalyzed Cyclization of 4‐Allenyl‐2‐azetidinones

Abstract

Bicyclic β lactams are obtained by the two-step procedure shown in the scheme. Alternatively, with the help of organoindium reagents, allenyl and propargyl groups are introduced at the C4-position of 2-azetidinones. R1=H, 1R-(tert-butyldimethylsilyloxy)ethyl (TBSO(CH3)CH); R2=H, methyl, ethyl, n-butyl, phenyl, THPOCH2, trimethylsilyl, 2-naphthyl; R3=H, methyl, phenyl; R4=H, methyl.