Synthesis of 2-Oxopyrrole-fused 1,n-Diazaheterocyclic Compounds and Substituted 2-Oxopyrroles via a Three-Component Reaction

An effective route to 2‐oxopyrrole‐fused 1,n‐diazaheterocyclic compounds and substituted 2‐oxopyrroles is described. This involves reaction of 1,n‐diamines or monoamines 1 and nitroketene dithioacetal (1,1‐di(methylthio)‐2‐nitroethene) in the presence of dialkyl acetylenedicarboxylate 2 in EtOH to give 2‐oxopyrrole derivatives 3 in good yields (Table 1). The structures were corroborated spectroscopically (IR, 1H and 13C NMR, and EIMS) and by elemental analyses. A plausible mechanism for this type of cyclization is proposed (Scheme 1).