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.
Synthesis of 2-methylidene-1-silacyclohexanes from 2,6-dibromohex-1-ene and polyhalosilanes
作者:Silvia Díez-González、Luis Blanco
DOI:10.1016/j.jorganchem.2006.08.061
日期:2006.12
Various 2-methylidene-l-silacyclohexanes were prepared by straightforward syntheses from readily available polychloro- or polyfluorosilanes, magnesium and 2,6-dibromohex-l-ene using Barbier-type conditions or a previously synthesized Grignard reagent. Good yields were obtained considering the low stability of the products in the reaction conditions. (c) 2006 Elsevier B.V. All rights reserved.
SHI, L.;NARULA, C. K.;MAK, K. T.;KAO, L.;XU, Y.;HECK, R. F., J. ORG. CHEM., 1983, 48, N 22, 3894-3900
作者:SHI, L.、NARULA, C. K.、MAK, K. T.、KAO, L.、XU, Y.、HECK, R. F.