Cross-coupling reactions with organometallic reagents

Cross-coupling reactions with organometallic reagents... 

These vinyl sulfoximines undergo nickel-catalyzed cross-coupling reactions with organometallic reagents to give optically active alkenes (see Section V.D for details). 

C-C/C-N Cross-Coupling Reactions with Organometallic Reagents... 

Nickel and Palladium Complex Catalyzed Cross-Coupling Reactions of Organometallic Reagents with Organic Halides. 

M. Kumada, Nickel and Palladium Cross-Coupling Reactions of Organometallic Reagents with Organic Halides , Pure Appl. Chem., 1980, 52, 669. 

The cross-coupling reactions of organometallic reagents with organic electrophiles in the presence of transition state metal catalysts, based mostly on nickel or palladium metal, has emerged as a powerful tool for the synthesis of both natural and unnatural compounds. Great advances in the field have included the development of new metal complexes for asymmetric catalytic reactions that can be carried out under mild conditions even with deactivated or steri-cally hindered substrates. 

As well as alkenylstannanes [106-108], other classes such as a-heteroatom-substituted alkyltributylstannanes [109] and, more importantly, allylic stannanes [110, 111] also undergo these Sn-Cu transmetalations. Otherwise difficult to prepare, allylic copper reagents may, however, be obtained by treatment of allylic stannanes (produced in turn from organolithium, magnesium, or zinc organometallics) with Me2CuLi LiCN. They enter into cross-coupling reactions with alkyl bromides [110] or vinyl triflates (Scheme 2.52) [111]. 

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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