Direct Synthesis of Polyfunctionalized Unsaturated δ-Lactones and δ-Lactams from α-Alkenoyl α-Carboxyl/Carbamoyl Ketene S,S-Acetals under Vilsmeier Conditions

An efficient method for direct synthesis of polyfunctionalized unsaturated delta-lactones 2 and delta-lactams 4 has been developed from the reaction of the easily available alpha-alkenoyl alpha-carboxy/carbamoyl ketene S,S-acetals 1/3 and Vilsmeier reagents (DMF/POCl3 or DMF/PBr3) via a cyclization followed by a halovinylation or haloformylation sequence.