Ni-Catalyzed Arylbenzylation of Alkenylarenes. Kinetic Studies Reveal Autocatalysis by ZnX2 and 3-Fold Catalytic Rate Increase

We report a Ni-catalyzed regioselective arylbenzylation of alkenylarenes with benzyl halides and arylzinc reagents. The reaction furnishes differently substituted 1,1,3-triarylpropyl structures that are reminiscent of the cores of oligoresveratrol natural products. The reaction is also compatible for the coupling of internal alkenes, secondary benzyl halides and variously substituted arylzinc reagents. Kinetic studies reveal that the reaction proceeds with a rate-limiting single electron transfer process and is autocatalyzed by in situ-generated ZnX2. The reaction rate is amplified by three-fold through autocatalysis upon addition of ZnX2.