Grignard reagents coupling reactions with alkyl halides

Alkanes can also be prepared from alkyl halides by reduction, directly with Zn and acetic acid (AcOH) (see Section 5.7.14) or via the Grignard reagent formation followed by hydrolytic work-up (see Section 5.7.15). The coupling reaction of alkyl halides with Gilman reagent (R 2CuLi, lithium organocuprates) also produces alkanes (see Section 5.5.2). 

Tamura and Kochi studied the cross-coupling reactions of alkyl halides with alkyl Grignard reagents catalyzed by silver compounds first [422, 426, 427]. The coupling of primary alkyl halides with primary Grignard reagents resulted in a mixture... 

Cross coii ing of Grignard reagents with 1-alkenyl halides, in marked contrast to alkyl halides, occurs readily with the reduced iron catalyst, as described above. The iron-catalyzed reaction of Grignard reagents with 1-alkenyl halides can, however, be differentiated from the reaction with alkyl halides. Thus, a mixture of propenyl bromide and ethyl bromide on reaction with methylmagnesium bromide afforded butene-2 but no cross-over products such as pentene-2 or propylene. The latter certainly would have resulted if a propenyliron species per se were involved in the catalytic process. Cross coupling under tEese circumstances clearly merits further study. 

Cross-coupling reaction of alkyl halides with grignard reagents in the presence... 

CROSS-COUPLING REACTION OF ALKYL HALIDES WITH GRIGNARD REAGENTS IN THE PRESENCE OF 1,3-BUTADIENE CATALYSED BY NICKEL, PALLADIUM, OR COPPER... 

Cross-Coupling Reaction of Alkyl Halides with Grignard Reagents Catalyzed by Ni, Pd, or Cu Complexes with n-Carbon Ligand(s) Terao, J. Kambe, N. Acc. Chem. Res. 2008,... 

Reaction with Alkyl Halides. The Grignard reagent (1) can be alkylated by allyl halides to afford the homoallylsilane. The use of a nickel(II) catalyst facilitates coupling of the Grignard reagent (1) to vinyl halides and aryl halides, triflates and O-carbamates and provides a useful method for the preparation of allyl- andbenzylsilanes (eq 7). Palladium catalysis is also effective to couple (1) with vinyl halides. 

Another type of Grignard reaction is the alkylation with alkyl halides. Upon treatment of a Grignard reagent RMgX with an alkyl halide 5, a Wwrtz-like coupling reaction takes place. 

Polarization also occurs in coupling and disproportionation reactions of Grignard reagents with alkyl halides. The vinyl protons of isobutene produced in the reaction of t-butylmagnesium chloride with t-butyl bromide show A/E polarization as do the methyl protons of isobutane (Ward et al., 1970). Similar results arise in the reaction of diethyl-magnesium with organic halides (Kasukhin et al., 1972). 

Scheme 29 Iron-catalyzed cross coupling reaction of aryl Grignard reagents with alkyl halides...

---