Synthesis of Isochromeno[3,4-d]imidazoles via Rh(II)-catalyzed [3+2] Annulation between 4-Diazoisochroman-3-imines and Oximes

A series of isochromeno[3,4-d]imidazoles were synthesized in good yields via Rh(II)-catalyzed [3+2] annulation between 4-diazoisochroman-3-imines and oximes. This method involves the formation of rhodium carbene intermediates and elucidates the unique reactivity of oximes under Rh(II) catalysis. Operationally simple and mild reaction conditions with broad substrate diversity, and readily accessible starting materials and rhodium catalyst are the merits of our reaction.