Acid-promoted oxidative methylenation of 1,3-dicarbonyl compounds with DMSO: application to the three-component synthesis of Hantzsch-type pyridines

A highly convergent one-pot synthesis of Hantzsch-type pyridines has been developed based on a three-component annulation of 1,3-dicarbonyl compounds, DMSO, and ammonium salt. A transition-metal-free oxidative methylenation reaction/Hantzsch pyridine synthesis cascade reaction was involved in this process. This intermolecular annulation reaction proceeds under mild reaction conditions, wherein DMSO serves as solvent, carbon source, and oxidant. A series of polysubstituted pyridines and methylene-bridged bis-1,3-dicarbonyl compounds were prepared in high yields.