T-Butyldiphenylsilyl ethers

Desilylation. On treatment with Me SiOTf and then MeOH t-butyldimethylsilyl ethers are hydrolyzed chemoselectively. t-Butyldiphenylsilyl ethers are not affected. 

In connection to the above reactions, methylenation of dimethyl acetals 48 instead of ketones can be conveniently performed by the reaction with McgSiCHg-Cu(PBu3) LiI 47, which is prepared in situ from MegSiCHgLi, Cul, and PBug under the influence of BFg-OEtg (Scheme 2.31) [86]. Methylenation is successful with ketone acetals 48 even when they bear protected hydroxy functions, such as benzyl ether, benzoate, and t-butyldiphenylsilyl ether. The reactions proceed by way of Lewis acid promoted j8-elimination of a j8-alkoxysilane. 

Table 2 compares the rate of hydrolysis of several bulky silicon ethers with acid, base, and fluoride TBDMS ethers are less resistant to hydrolysis than the corresponding TIPS (triisopropylsilyl) and TBDPS (t-butyldiphenylsilyl) ethers. 

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