Substitution trimethylsilyloxy-substituted alkene

Trimethylsilyloxy-substituted alkenes are by far the most widely used enol ethers because of their straightforward preparation from the corresponding ketones (equation 20)78-82 -pjjg electron-rich character of silyl enol ethers allows for highly chemoselective cyclopropanations in the presence of additional double bonds (eqnation 21). ... 

Many synthetic applications have been reported of the photochemical reactions of halogen-substituted 1,4-naphthoquinones with 1,1-diarylethenes487 90, and with related electron-rich alkenes such as 1-aryl-l-trimethylsilyloxyethenes491 93, 2-trimethylsilyloxy-1-alkenes494, 2-methoxy-l-alkenes495 and allyltributylstannane496,497. The process is exemplified by the reaction of 2-bromo-3-methoxy-1,4-naphthoquinone derivatives (152) with 1,1-diphenylethene487 (equation 129). 

Reactions of various activated alkenes with Mg/TMSCl in DMF system have been explored as well. When treated with this reduction mixture, a-substituted arylvinyl sulfones affords ( )-/3-substituted st)renes in high stereoselectivity and reasonable yields, through the desulfonation reaction (eq 83). Under the reaction conditions, Q ,/3-unsaturated ketones undergo facile and regioselective reductive dimerization to afford the corresponding bis(silyl enol ethers), that is, l,6-bis(trimethylsilyloxy)-1,5-dienes (eq 84) In contrast, Q ,/3-unsaturated esters or a,/3-epoxy... 

Marko and co-workers extended their hydrosilylation reactions of alkenes to terminal alkynes. Initially, complexes of 133-type were screened in the hydrosilylation of 1-octyne by bis(trimethylsilyloxy)methylsilane as the model reaction and enhanced selectivity was observed when bulky aryl substituted NHCs were employed (IPr and SlPr). ... 

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