Homoallyl alcohols intramolecular hydrosilations

Intramolecular hydrosilation. Tamao et al. have extended their hydrosily-lation-oxidation sequence (12,243-245) to allyl and homoallyl alcohols as an approach to 1,3-diols. When applied to cyclic homoallylic alcohols, only a cis-1,3-diol is obtained, presumably by way of a cyclic intermediate (equation I). Acyclic homoallylic alcohols can be converted by this approach to either syn- or anti-1,3-... 

The C—Si bond formed by the hydrosilation of alkene is a stable bond. Although it is difficult to convert the C—Si bond to other functional groups, it can be converted to alcohols by oxidation with MCPBA or H2O2. This reaction enhances the usefulness of hydrosilylation of alkenes [219], Combination of intramolecular hydrosilylation of allylic or homoallylic alcohols and the oxidation offers regio- and stereoselective preparation of diols [220], Internal alkenes are difficult to hydrosilylate without isomerization to terminal alkenes. However, intramolecular hydrosilation of internal alkenes can be carried out without isomerization. Intramolecular hydrosilylation of the silyl ether 572 of the homoallylic alcohol 571 afforded 573 regio- and stereoselectively, and the Prelog-Djerassi lactone 574 was prepared by applying this method. 

Intramolecular Hydrosilation of Allyl and Homoallyl Alcohols. For a detailed description of the intramolecular hydro-silation-oxidation sequence, see 1,1,3,3-tetramethyldisilazane. 1,1,3,3-Tetramethyldisilazane and AA -diethylaminodimethyl-silane are frequently employed for preparation of hydrodimethyl-silyl ethers for the intramolecular hydrosilation of allyl and homoallyl alcohols. Chlorodimethylsilane in combination with a tertiary amine such as triethylamine is another useful reagent for the synthesis of hydrodimethylsilyl ethers, especially for large scale preparations. ... 

Intramolecular Hydrosilation Agent. For a detailed description of the intramolecular hydrosilation procedure, see 1,1,3,3-tetramethyldisilazane. lV,lV-Diethylaminodimethylsilane is a useful reagent for the conversion of hydroxy groups of allyl or homoallyl alcohols into hydrodimethylsilyl ethers for use in intramolecular hydrosilation reactions. In some cases, lV,lV-dieth-ylaminodimethylsilane gives superior results compared to the more commonly employed 1,1,3,3-tetramethyldisilazane (eq 1). ... 

Intramolecular Hydrosilation. Allyl and homoallyl alcohols are transformed into 1,3-diols in a highly regio- and stereoselective fashion via intramolecular hydrosilation followed by oxidative cleavage of the silicon-carbon bonds by hydrogen peroxide, which proceeds with complete retention of configuration at carbon (eqs 1 and 2). ... 

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