An Unusual I2/Base-Catalyzed C(sp3)-H Chalcogenation of Cyclohexanone-Fused 4-Hydroxy-2-pyridones and Extension to
Arun Dhurey1, Animesh Pramanik1
1Department of Chemistry, University of Calcutta, 92, A. P. C. Road, Kolkata 700009, India.
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.
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