Enantioselective Alkylation of Unactivated C–O Bond: Solvent Molecule Affects Competing β-H Elimination and Reductive Elimination Dynamics

Abstract

Despite the fact that metal-catalyzed asymmetric alkylative cross-couplings have been well-established, enantioselective alkylative substitution of an unactivated C–O bond remains a challenge due to the lack of strategies to cleave the C–O bond and suppress β-H elimination as well as control stereochemistry simultaneously. Herein, the enantioselective alkylative activation of an unactivated C–O bond with β-H-containing alkylating reagents was described using a chiral nickel catalyst, and versatile axially chiral biaryls bearing alkyl moieties with different chain lengths were delivered in good yields and with high ee. Control experiments demonstrated the significant role of the solvent tetrahydrofuran to facilitate this transformation. DFT calculations revealed that the coordination of THF to Mg(II) is pivotal for suppressing β-H elimination during reductive elimination, thus unlocking how the solvent molecule affects the competing β-H elimination and reductive elimination dynamics in transition-metal-catalyzed alkylative cross-coupling reactions.