One‐Pot Two Step Nazarov‐Schmidt Rearrangement for the Synthesis of Fused δ‐Lactam Systems

In this article we have described a method to synthesize fused δ‐lactam compounds from chalcones, via a one pot two step route, involving consecutive application of Nazarov and Schmidt rearrangement reactions. Initial studies were done on 3‐phenyl‐1‐(thiophen‐3‐yl)prop‐2‐en‐1‐one, using polyphosphoric acid (PPA) and sodium azide at 120 ° C, whence the unexpected N ‐alkyl amide product was obtained, instead of usual N ‐aryl analogue. With diverse 3‐aryl substituted‐1‐(thiophen‐3‐yl)prop‐2‐en‐1‐one and 3‐aryl substituted‐1‐(thiophen‐2‐yl)prop‐2‐en‐1‐one as substrates, corresponding N ‐alkyl amide compounds were obtained in modest to good yields. Interestingly, with 3‐aryl substituted phenylprop‐2‐en‐1‐one as substrates under the optimized conditions, N ‐aryl amide compounds were formed as the final products instead of corresponding N ‐alkyl analogues.