Vinyl siliconates, cross-coupling reaction

It is a palladium-catalyzed cross-coupling reaction between organosilanes (vinyl, ethynyl and allylsilanes) and organic halides (aryl, vinyl and allyl halides). Allylpal-ladium chloride dimmer [( ri -C3H5PdCl)2] and either tris(diethylamino)sulfonium difluorotrimethylsilicate (TASF) or tetra-n-butylammonium fluoride (TBAF) are used as catalysts. Fluoride ion acts as an activator for the coupling, forming an intermediate hypervalent anionic silicon species, which can then transmetallate with palladium as a preliminary reaction to coupling. 

The same reaction conditions were applied to the coupling reaction of Trimethyl(vinyl)silane [Eq.(3)] with limited success [3], Thus, the mechanism of these silicon-based reactions appears to be different from those of the cross-coupling reactions using the main-group metal reagents. 

Summary Recent achievements in two catalytic reactions, i.e., silylative coupling and cross-metathesis of alkenes and dienes with vinyl-silicon compounds, which resulted in new synthetic routes to organosilicon molecular and macromolecular compounds are presented. The silylative coupling, also called dehydrogenative or trans-silylation and silyl group transfer, is catalyzed by metal complexes which either contain or initiate the formation of M-H and M-Si bonds, where M = Ru, Rh, Co and Ir. Cross-metathesis, which was developed very recently, proceeds in the presence of metallacarbenes, mainly those of rathenium (e.g., Grabbs catalyst). 

With the discovery of the Hiyama reaction other cross-coupling partners such as organosilicon derivatives have recently emerged as excellentreagents. 75 Various silicon substituted derivatives are suitable for transmetallation step when fluoride ions are added in the reaction medium. Organofluorosilanes bearing aryl, vinyl, or... 

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