Grignard reagents aryl-alkenyl reactions

Nickel(II) salts are able to catalyze the coupling of Grignard reagents with alkenyl and aryl halides. A soluble 6 -phosphine complex, Ni(dppe)2Cl2, is a particularly effective catalyst.266 The main distinction between this reaction and Pd-catalyzed cross... 

Organotins. The organotin reagents have much lower nucleophilicity than that of the Grignard reagents, thus allowing the use of a variety of functionalized monomers for the polymerization. Aryl-alkenyl iodides, bromides and tosylates have been used as substrates. Palladium complexes are commonly employed as catalysts for the reaction. Because the catalysts can be destroyed... 

Corey and Posner discovered that lithium dimethylcuprate could replace iodine or bromine by methyl in a wide variety of compounds, including aryl, alkenyl, and alkyl derivatives. This halogen displacement reaction is more general and gives higher yields than displacements with Grignard or lithium reagents.20... 

Aryl and alkyl organozincate reagents, generated in situ by reaction of Grignard reagents and sub-stoichiometric amounts of ZnCl2, cross-couple smoothly in refluxing THF with functionalized aryl and alkenyl as well as primary and secondary alkyl chlorides in the presence of Pd(dppf)Cl2. ... 

In 2002, Figad re and coworkers reported the mono-reduction of 2-aryl (or heteroaryl)-1,1-dibromo-l-alkenes (Scheme 23). The reaction is achieved with one equivalent of isopropylmagnesium chloride in the presence of iron(III) acetylacetonate. Pure ( )-alkenyl bromides are obtained. With two equivalents of alkyl Grignard reagent, the mono-substituted product is obtained in moderate yield. 

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