Cross-coupling reactions diorganozinc preparation

The more difficult cross-coupling reaction between Csp -Csp can be accomplished by mixed zincate compounds, prepared by the reaction of diorganozinc derivatives with Me2CuMgCl-MgCl(CN) (equation 59). Substitution reaction at Csp centers are also efficiently catalyzed by Ni salts when the alkyl halide contains a double bond in remote position (Scheme 22). Changing the double bond for a triple bond leads to an intramolecular carbozincation reaction (equation 60). 

A major part of this chapter will show the synthetic applications of these transmetallation reactions for the perfonnancc of cross-coupling reactions. After a short description of the methods of preparation of organozinc halides (RZnX) and diorganozincs (R2Zn), the utility of these reagents for forming new carbon-carbon bonds will be presented. Emphasis will be... 

Then, the use of nickel(II) or cobalt(II) complexes as catalyst associated to the sacrificial anode process allows synthesis of functionalized mono- or diorganozinc species in a simple and efficient manner. Alternating Jt-conjugated copolymers, based on this electrochemical preparation of intermediate aryldizinc species and their subsequent palladium-catalyzed coupling with unsaturated dihalogenated compounds, can be synthesized. Furthermore, aromatic ketones are synthesized efficiently via cobalt-catalyzed cross-coupling reaction between arylzinc bromides and acid chlorides. 

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