Organosilicon-based coupling reaction

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. 

Previous studies on organosilicon-based cross-coupling reactions. . . 421... 

Previous Studies on Organosilicon-based Cross-coupling Reactions... 

The Future of the Organosilicon-based Cross-coupling Reaction... 

The organosilicon-based cross-coupling reactions discussed here are summarized in Eq.(42). The number of fluorine atom on silicon depends on the substituent which participates in the coupling reaction. 

The use of alkenylsilyl ethers in palladium-catalyzed cross-coupHng reactions has long been known. In fact, only a year after Hiyama s landmark report on the TBAF-promoted coupling reactions of vinyltrimethylsilane, Tamao and Ito capitahzed on the use of alkoxy-substituted silanes as viable components for such reactions (cf Scheme 7.4). The generahty of the silyl ether coupHng added a useful class of organosilicon substrates that are complementary to the fluorosilanes developed by Hiyama et al. These studies showed that other heteroatom-based... 

In the course of studies on organosilicon-based cross-coupling reactions, Denmark and co-workers found that vinyldisiloxanes and vinylpolysiloxanes are competent organometallic donors. A series of commercially available di- and poly vinylsiloxanes are effective in the palladium-catalyzed cross-coupling reaction with 4 -iodoacetophenone (5, Table 1 eq 1). 

The application of bases other than fluoride for activation of organosilicon compounds to crosscoupling is documented. NaOH can replace fluoride in the cross-coupling of aryl and alkenyldichloroalkylsilanes with aryl halides, including chlorides. Apart from providing milder reaction conditions, the reaction in the presence of NaOH is applicable to a wider range of substrates ((85) and (86)).294... 

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