A Novel and Efficient Synthesis of Pyrido[1,2‐ a ]‐Fused 1,3‐Diazaheterocyclic Compounds via a One‐Pot Three‐Component Reaction

An efficient one‐pot synthesis of pyrido[1,2‐ a ]‐fused 1,3‐diazaheterocyclic compounds by three‐component reaction of diamine, nitroketene dithioacetal (=1,1‐bis(methylsulfanyl)‐2‐nitroethene), and electron‐poor itaconic anhydride (=2‐methylidenesuccinic anhydride=2‐methylidenebutanedioic anhydride) in aqueous EtOH is reported. This protocol has the advantages of easiness, higher yields, and shorter reaction times. The structures were corroborated spectroscopically (IR, 1 H‐ and 13 C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this type of cyclization is proposed ( Scheme 2 ).