Diastereoselectivity in the Epoxidation of Substituted Cyclohexenes by Dimethyldioxirane1,2
摘要:
Three series of compounds based on the cyclohexene framework. have been epoxidized by dimethyldioxirane. A pronounced dependence of epoxide diastereoselectivity on substituent has been observed. In addition there is a solvent influence on this stereoselectivity. The results have been explained by invoking steric, H-bonding, and dipole-dipole influences on the epoxide stereochemistry.
Cross-coupling reactions between some allyl, homoallyl, and homopropargyl substrates and trialkylalanes or dialkyl- and diaryl-magnesium derivatives *
作者:G.A. Tolstikov、U.M. Dzhemilev
DOI:10.1016/0022-328x(85)87328-9
日期:1985.9
Trialkylalanes and dialkyl- and diaryl-magnesium derivatives can be cross-coupled with allyl ethers and esters, sulphides, and quaternized allylamines. The reactions proceed uncatalyzed either with mild conditions or in the presence of copper complex catalysts to result in high yields of mono- and di-olefins of various structures.
Cu-catalyzed AAA reactions employing racemic cyclicallylic bromide and extremely reactive organolithium reagents as reaction partners have been disclosed. The corresponding alkylated products were obtained with high enantioselectivities (up to 98 % ee).