α-Sulfenylation of acylsilanes and aldehydes with N-(phenylthio)succinimide
摘要:
The reactions of acylsilanes with N-(phenylthio)succinimide in the presence of p-toluenesulfonic acid in acetonitrile give alpha-sulfenylated acylsilanes in good yields. Aldehydes with alpha-alkyl substituent afford moderate yields of alpha-sulfenylated products under the same conditions. (C) 2000 Elsevier Science Ltd. All rights reserved.
5-Exo cyclizations of primary and secondary radicals with acylsilanes successfully give cyclopentyl silyl ethers. The corresponding 6-exo cyclizations are sensitive to changes of the size of silyl groups. Secondary radicals undergo 6-exo cyclizations with acylsilanes more slowly. Reaction of aryl radical with acylsilane proceeds well for 5-exo cyclization but not for 6-exo cyclization. Vinyl radicals give best results in 5-exo cyclizations with acylsilanes but give low yields (similar to 30%) in 6-exo cyclizations. Intramolecular cyclizations of vinyl radicals with acylsilanes give enol silyl ethers regiospecifically.
Radical cyclizations of bromo acylsilanes and intramolecular trapping of the rearranged α-silyloxy radicals
作者:Yeun-Min Tsai、Kuo-Hsiang Tang、Weir-Torn Jiaang
DOI:10.1016/s0040-4039(00)91780-5
日期:1993.2
Radical 1,5-exo cyclizations of acylsilanes involving secondary radicals are quite effective. In contrast, 1,6-exo cyclizations are more sensitive toward steric effect. Tandem radical cyclization process can be designed.