Transition Metal‐Free sp3−sp3 Carbon‐Carbon Coupling between Benzylboronic Esters and Alkyl Bromides

A transition metal‐free coupling reaction of benzylboronic esters and alkyl halides has been developed. Both alkyl bromides and alkyl iodides were found to be competent substrates with the nucleophilic boronate intermediate generated from the combination of benzylboronic ester and an alkyllithium. Good chemoselectivity was observed for the reaction with the alkyl bromide in substrates with a second electrophile present. Both secondary and tertiary benzylboronic esters were effective nucleophiles in the reaction with primary alkyl halides. Mechanistic observations are consistent with a radical mechanism. An sp3−sp3 transition metal‐free coupling between benzylic boronic esters and alkyl halides has been demonstrated. The boronate nucleophile reacts selectively with alkyl bromides in the presence of alkyl chlorides and epoxides. The boronate can be attached to a primary, secondary and tertiary carbon center, providing the desired coupled products in good to excellent yields.