The sisyl (tris(trimethylsilyl)silyl) group: A fluoride resistant, photolabile alcohol protecting group
作者:Michael A. Brook、Christine Gottardo、Sonya Balduzzi、Mustafa Mohamed
DOI:10.1016/s0040-4039(97)01673-0
日期:1997.10
The use of the tris(trimethylsilyl)silyl (sisyl) group as a photolabile protecting group for primary and secondary alcohols was demonstrated. Sisyl ethers of a number of alcohols (yields 70-97%) were stable to many synthetic protocols, but could be deprotected using photolysis to give the starting alcohols (yields 62-95%). (C) 1997 Elsevier Science Ltd.
Alkoxyallylsilanes: Functional Protecting Groups
作者:Sonya Balduzzi、Michael A. Brook
DOI:10.1016/s0040-4020(99)01062-5
日期:2000.3
Allyl-t-butylmethylsilyl groups were shown to function as alcohol protecting groups whose hydrolytic stability was greater than t-butyldimethylsilyl (TBS) and Si(SiMe3)(3) (sisyl) groups. Pseudo-first-order rate constants for the acidic hydrolysis of primary, benzylic, and secondary allyl-t-butylmethylsilyl ethers in AcOD/THF-d(8)/D2O were determined to be 2.94x10(-3), 8.26x10(-4), and 8.26x10(-4)s(-1) respectively. The regioselectivity of acidic hydrolysis of allylbenzyloxy-t-butylmethylsilane 1 was examined under strong acid (p-TsOH/ CD2Cl2) and weak acid (AcOD/HF-d(8)/D2O) conditions. In both cases, benzyl alcohol was initially produced exclusively from silicon-oxygen bond cleavage: allylic cleavage was only subsequently observed over time. However, the allyl group of the silyl ether could be hydrosilylated. The resulting alkoxy-functionalized disiloxane had greater hydrolytic stability under acidic conditions than the starting alkoxyallyl-t-butylmethylsilane. (C) 2000 Elsevier Science Ltd. All rights reserved.