Stereodivergent Synthesis of BothZ- andE-Alkenes by Photoinduced, Ni-Catalyzed Enantioselective C(sp3)–H Alkenylation

The enantio- and stereoselective synthesis of stereodefined alkenes, especially the functionalized Z-isomer with an allylic stereogenic center, remains a great challenge. We herein report an enantioselective benzylic C(sp3)–H alkenylation of simple alkylarenes with vinyl bromides via photoinduced nickel catalysis, which allows for the stereodivergent synthesis of both enantioenriched Z- and E-alkenes bearing aryl-substituted, allylic tertiary stereogenic centers. Interestingly, the tunable Z/E-selectivity is achieved by energy transfer catalysis via a judicious choice of the photocatalyst counteranion. This versatile strategy features simple starting materials, mild reaction conditions, broad substrate scope, divergent Z- and E-selectivity, and high enantioselectivities. Moreover, a formal asymmetric benzylic C(sp3)–H alkylation can also be achieved via a one-pot alkenylation/reduction sequence, providing a complementary strategy to address the notoriously challenging stereochemical control in C(sp3)–C(sp3) bond construction.