Rh(III)-catalyzed relay carbenoid functionalization of aromatic C-H bonds: access to π-conjugated fused heteroarenes.

A novel Rh(III)-catalyzed relay cross-coupling/cyclization cascade between arylketoimines and diazoesters is described. This transformation provides a concise access to unique π-conjugated 1-azaphenalenes (1-APLEs) via a double aryl Csp(2)-H bond carbenoid functionalization process. As illustrative examples, the 1-APLE-based π-conjugated molecules which possess low-lying HOMO levels could be converted to promising organic optoelectronic materials.