Mechanism

ArBr can undergo coordination with in situ generated Ni(0) complex that could lead to oxidative addition to give the intermediate I. The latter may undergo reaction with ArMgBr to replace the bromide to give the intermediate II (transmetallation) that could complete the catalytic cycle by reductive elimination of the target biaryl product.
The C-C cross-coupling of secondary alkylmagnesium halide may occur in analogy to the reaction of the primary alkylmagnesium halide (Scheme 10), but they may also lead to the unexpected reactions depending on the catalytic system due to steric hindrance that could lead to isomeriazation of the C-C coupling (Scheme 11).

Scheme 11

3.1.1.5 Special Applications
 Synthesis of Ethers

Organomagnesium halides with lower halogenated ethers produce higher ester (Scheme 12).

Scheme 12

Synthesis of Stilbene
The synthesis of stilbene can be accomplished by the reaction of benzylmagnesium bromide with benzaldehyde, followed by dehydration (Scheme 13).

Scheme 13

 

Synthesis of Alkyl cyanide

The reaction of alkylmagnesium halides with cyanogens or cyanogens chloride gives alkyl cyanides (Scheme 14).

Scheme 14