Cross-Coupling of α-carbonyl sulfoxonium ylides with C-H bonds

The functionalization of carbon-hydrogen bonds in non-nucleophilic substrates using α-carbonyl sulfoxonium ylides has not been so far investigated, despite the potential safety advantages that those reagents would provide over diazo compounds or their in situ precursors. We describe the cross-coupling reactions of sulfoxonium ylides with C(sp2)-H bond of arenes and heteroarenes in the presence of a rhodium catalyst. The reaction proceeds by a succession of C-H activation, migratory insertion of the ylide into the carbon-metal bond and protonation, the last step being turnover-limiting. The method is applied to the synthesis of benz[c]acridines when allied to an iridium-catalyzed dehydrative cyclization