Tandem Conjugate Carbon Addition–Intermolecular Hetero Diels–Alder Reactions using Ethyl 1H-Perimidine-2-acetate as a Ketene Aminal with Heating or Microwave Activation†

Abstract

The reaction of ethyl 1H-perimidine-2-acetate 3 as a heterocyclic ketene-aminal with 2.1 equiv. of ethyl propiolate 4a or but-3-yn-2-one 4b affords new fused perimidines in good yields by a tandem C-addition/hetero Diels–Alder reaction; the new 1-azabuta-1,3-diene intermediates are generated in situ from the initial trans C-addition products by thermal 1,5-prototropy.