Epoxidation 2,2-disubstituted vinylsilane

The substrate scope of this epoxidation was subsequently investigated using a variety of olefins with a catalytic amount of ketone 1 (usually 20-30 mol%). A variety of hms-substituted and trisubstituted olefins have been shown to be effective substrates (Table 10.1),39 and the high ee obtained with hms-7-tetradecene suggests that this epoxidation is quite general for simple trans-olefins (Table 10.1, Entry 5). Various functional groups such as ethers, ketals, esters, and so on are compatible with the epoxidation conditions (Table 10.1). A variety of 2,2-disubstituted vinylsilanes... 

Shi s chiral ketone (21) catalyses the asymmetric epoxidation of 2,2-disubstituted vinylsilanes by Oxone. Enantioselectivity is presumed to be better when the spiro, rather than the planar, transition state is operating. This is probably favoured when the 2-substituents are less bulky and the planar transition-state is disfavoured by bulky silyl substituents. ... 

Warren JD, Shi Y. Chiral ketone-catalyzed asymmetric epoxidation of 2, 2-disubstituted vinylsilanes. J. Org. Chem. 1999 64(20) 7675-7677. 

Scheme 3.30 Epoxidation of 2,2-disubstituted vinylsilanes with ketone 39 [43]...

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