Nickel-Catalyzed Coupling of Alkyl Halides and Alkyl Grignard Reagents

Key words

alkyl halides - cross-coupling - Grignard reagents - nickel complexes

Significance

Grignard reagents are desirable nucleophiles in coupling reactions, since they are inexpensive and easy to prepare. The use of a
pincer nickel complex (1) enables their highly efficient sp^³-sp^³ cross-coupling with alkyl bromides and iodides. The reaction proceeds at low temperatures, so that even highly reactive functionalities like ketones are tolerated.

Comment

Alkyl bromides and alkyl iodides react at similar rates, while alkyl chlorides are inert. Interestingly, aryl bromides do not participate in the coupling under these conditions. N,N-Dimethyl­acetamide (its mixture with THF) is the solvent of choice, NMP and other solvents give lower yields. Nickel(IV)-bis(alkyl) intermediates are tentative
intermediates in this reaction.