Synthesis coupling reactions with organometallics

Application of Transition Metal Catalysts in Organic Synthesis, Springer, Berlin, 1998, 227-275. Nickel- and Palladium-Catalyzed Cross-Coupling Reactions with Organometallic Intermediates. 

The stereodefined alkenyl halides are of prime importance due to the recent developments of di- or trisubstituted alkene synthesis by cross-coupling reactions between organometallics and alkenyl halides catalyzed by transition metal compounds 171). These alkenyl halides can be conveniently obtained from alkenylboranes or alkeneboronic acids. B-Alk enylcatecholboranes undergo rapid hydrolysis when stirred with excess water at 25 °C (Eq. 109)102). The alkeneboronic acids are usually crystalline solids of low solubility in water and can be easily isolated and handled in air without significant deterioration. 

The cross-coupling reaction with non-activated iodoalkenes proceeds well only by using a polar solvent like NMP or DMPU [29] and elevated reaction temperatures (60 °C, 12 h). The compatibility of the zinc-copper reagents with these harsh reaction conditions shows the remarkable thermal stability of zinc-copper organometallics. The cross-coupling reaction occurs with complete retention of the configuration of the double bond and allows the stereospecific synthesis of highly functionalized alkenes like 29 (see Section 9.6.6 Scheme 9-27) [57],... 

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