Hydrosilylation enolate formation

In a side reaction enolizable ketones may give rise to varying amounts of silyl enol ethers. On hydrolysis, these silyl enol ethers are reconverted into the starting material. Thus, even on complete hydrosilylation, product formation is not quantitative and the secondary alcohol is accompanied by the ketone to the extent in which the silyl enol ether was formed. Thus, the hydrosilylation of 1-phenylethanone and its enol form with diphenylsilane affords the corresponding silyl ether and silyl enol ether and subsequent hydrolysis gives 1-phenylethanol and 1-phenylethanone13. 0 0H... 

During a synthesis of pederol dibenzoate, a key step required formation of a regiospecific enol silyl ether in a highly oxygenated and base-sensitive substrate. The reaction was uniquely achieved by a rhodium(i)-catalysed hydrosilylation sequence (Scheme 47). ... 

Hydrosilylation in the presence of a carbon electrophile is often accompanied by C-C bond formation. For example, three-component coupling of hydrosilane, alkyne, and y unsaturated aldehyde is suggested to proceed via oxanickelacycle intermediate to give (Z)-enol silyl ether (Scheme 3-28). Hydrosilylation of alkenes under a carbon monoxide atmosphere allows carbonyl incorporation, giving silyl enol ethers by using a cobalt or iridium catalyst (Schemes 3-29 and 3-30). Under similar reaction conditions in the presence of a rhodium catalyst, alkynes are converted to y silyl-substituted acroleins (Scheme 3-31). ... 

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