Ring‐Rearrangement Driven Formal (3 + 2) Cycloaddition of Enaminone‐Based Thioalkynes with Nitriles to Form Thiazole Containing Bis‐Heterocycles

Herein, a one‐pot synthesis of 3,4‐dihydropyridin‐2(H)‐one containing thiazole derivatives is reported by Bronsted acid‐mediated ring‐rearrangement and formal (3 + 2) cycloaddition reaction of enaminone‐based thioalkyne with alkyl/aryl nitrile. The developed protocol demonstrates a wide substrate scope for both the reacting partners with high atom‐economy furnishing very high to excellent yields of pharmaceutically relevant bis‐heterocyclic derivatives. Based on outcome of the product and control experiments, a plausible reaction mechanism has also been proposed. The gram‐scale synthesis and further synthetic transformation demonstrate the synthetic efficacy and utility of the developed protocol.