An Unusual I2/Base-Catalyzed C(sp3)–H Chalcogenation of Cyclohexanone-Fused 4-Hydroxy-2-pyridones and Extension to Several Cyano-Acetylated Derivatives

Abstract

A metal-free protocol has been developed for successive construction of C–C, C–N, and C–S/Se bonds to access unexpected C8-chalcogenated cyclohexanone-fused 4-hydroxy-2-pyridones in very good yields. This approach involves acetic anhydride-mediated condensation of enaminones of cyclohexa-1,3-dione and cyanoacetic acid to generate cyclohexanone-fused 4-hydroxy-2-pyridones that undergo I₂/K₂CO₃-catalyzed sulfenylation/selenylation at the C8 position instead of at the C3 position in the presence of thiophenols/selenols. This I₂/base-catalyzed method was further employed to achieve diverse C2-chalcogenated 2-cyano-N-aryl/alkylacetamides and indolyl-3-oxo-propanenitriles in good yields through generating the cyanoacetylated intermediates from easily available anilines, amines, and indoles.