Coupling reactions organosilicon reagents

Among other organosilicon reagents used for cross-couplings, notable ones are commercial vinylsiloxanes, which are useful for vinyl-transfer reactions (81).280... 

Reaction with Organosilicon Reagents (Hiyama Coupling) 668... 

Denmark SE, Ober MH. Organosilicon reagents synthesis and application to palladium-catalyzed cross-coupling reactions. Aldrichimica Acta 2003 36 75-85. 

Because a C-Si bond is much less polarized than the C-metal bonds of the above organometallic reagents, the cross-coupling reaction using organosilicon compounds was not studied until 1988. 

There has been controversy on the stereochemistry of the transmetallation of alkylmetals. Transmetallation from Hg to Pd is reported to proceed in THF with retention of configuration [27]. By contrast, cross-coupling reactions of organotin reagents are assumed to take place with inversion in HMPA [28] but with retention in toluene [29]. We consider that the organosilicon-based coupling reaction would be a useful model for examining the stereochemistry of the transmetallation process. 

We have found that alkynylsilanes are smoothly converted into alkynylcopper compounds by treatment with CuCl in l,3-dimethyl-2-imidazohdinone (DMI) the copper reagents can be isolated in good yields [563]. This study was the first example of preparation and isolation of organocopper compounds by use of organosilicon reagents. The Si-Cu transmetalation is applicable to the synthesis of alkynyl ketones by Cu-catalyzed alkynylation of acid chlorides (Scheme 10.217). We have also shown that a Cu-mediated system is effective in the cross-coupling reaction between arylsilanes or heteroarylsilanes and aryl hahdes [564]. 

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