Nickel-Catalyzed Coupling of Alkyl Halides and Alkyl Grignard Reagents

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

Significance

<P>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.</P>

Comment

<P>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.</P>