Study of Palladium-Catalyzed Site and Regioselective Reductive Heck Hydroarylation of Unactivated Alkene.

We studied the reaction pathway of our reductive Heck hydroarylation using a palladium catalyst and a hydrosilane. A key question to verify the reaction mechanism was which active species, Ar-Pd^II-I or Si-Pd^II-H, first performs migratory insertion into the alkenes. Identifying this step is crucial to elucidate the reaction mechanism. To address this, we designed a substrate containing two trisubstituted alkenes and tested its product. The results suggest that the migratory insertion of Ar-Pd^II-I into the alkene is the initial step of the reaction. Furthermore, this reaction can construct a quaternary carbon center and give high yields with high functional group tolerance.