Cp*IrIII-Catalyzed [3+2] Annulations of N-Aryl-2-aminopyrimidines with Sulfoxonium Ylides to Access 2-Alkyl Indoles Through C–H Bond Activation

The iridium-catalyzed aromatic C-H alkylation followed by intramolecular annulation reactions between N-aryl-2-aminopyridines and sulfoxonium ylides for the synthesis of 2-alkyl indoles is described. This highly efficient and step-economical cyclization reaction displays excellent functional group compatibility and regioselectivity. Afterwards, the directing group in C-H alkylation can be readily removed to obtain the free N-H indoles. Thus, the sulfoxonium ylide, a carbene precursor, is proved as a useful surrogate of diazo compounds in C-H activation chemistry.