Palladium/Silver Cocatalyzed Divergent Dimerization of 2H‑Azirines for Regioselective Synthesis of Tetrasubstituted Pyrroles and Pyrimidines

The unprecedented dimerizations of 2H-azirines have been developed under the catalysis of palladium and silver. Upon changing the reaction conditions, the fully aryl-substituted pyrrole and pyrimidine derivatives were furnished in moderate yields with regiospecificity, respectively. Control experiments uncovered distinct catalytic effects of two transition metals, and the proposed catalytic cycles plausibly rationalized the chemodivergence and regioselectivity.