Ethers, tribenzylsilyl

To control the stereochemistry of epoxidation at the 10,11-double bond in intermediates in prostaglandin synthesis, a bulky protective group was used for the C15-OH group. Epoxidation of the tribenzylsilyl ether yielded 88% a-oxide epoxidation of the tri-/ -xylylsilyl ether was less selective. ... 

The respective introducing reagents may also be sterically more demanding and give better selecti-vities in the protection of polyfunctional molecules. This is mainly exploited in nucleotide chemistry. Also, stereochemical bias may be introduced with the aid of appropriate silyl protection. As shown in equation (16), tribenzylsilyl and tri-p-xylylsilyl ethers were used to control the stereochemistry of epoxi-dation in prostaglandin syntheses. ... 

Protection of Alcohols. Tribenzylchlorosilane is highly reactive towards nucleophilic displacement of chloride ion," but it has found only limited application as a bulky silyl protecting group for alcohols. The protection of the allylic alcohol (1) as the tribenzylsilyl ether (2) (eq 1) allowed for high 7r-facial selectivity in a subsequent epoxidation reaction at the 10,11-double bond. The trihenzylsilyl ether group can be efficiently depro-tected to the free alcohol using ACOH/THF/H2O (3 1 1) at room temperature. ... 

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