α-Csp3-H Methylenation of Diketones to Synthesize Methylene-Bridged Bis-1,3-Dicarbonyl Compounds and Polysubstituted Pyridines Using the DMSO/Selectfluor System

A direct alpha-Csp(3)-H methylenation of 1,3-diketones to afford methylene-bridged bis-1,3-dicarbonyl derivatives using dimethyl sulfoxide (DMSO) as a one-carbon source was achieved in moderate to high yields in the presence of Selectfluor. The 1,3-diketones can also be efficiently converted into Hantzsch-type pyridines via one-pot three-component annulation reaction in the presence of DMSO and ammonium salt. The procedure avoids the use of transition metal catalysts and the reaction is efficient and operationally convenient.