Rhodium(III)-catalyzed direct selective C(5)-H oxidative annulations of 2-substituted imidazoles and alkynes by double C-H activation.

Double C-H activations of C(5)-H and Csp(2)-H of 2-substituted N-vinyl- or arylimidazoles were realized without heteroatom-directing assistance by rhodium(III) catalyst. A subsequent oxidative annulation reaction with alkynes efficiently produced aza-fused heterocycles with high molecular complexity in low to excellent yields.