Solvent microstructure effect on reaction stereochemistry; ring opening of chalcone oxides
作者:Dana Durham、Charles A. Kingsbury
DOI:10.1039/p29860000923
日期:——
The stereochemistry and kinetics of acid-catalysed ring-opening reactions of epoxides are reported. Predominant inversion is found in the usual hydroxylic solvents. As the nucleophilicity of the solvent diminishes and acidity increases, the stereochemistry changes to predominant retention. Electron-donating substituents also tend to favour retention. In mixed solvents, the solvent microstructure is
报道了酸催化环氧化物的开环反应的立体化学和动力学。在通常的羟基溶剂中发现主要的转化。随着溶剂的亲核性下降和酸度增加,立体化学改变为主要的保留。给电子的取代基也倾向于保留。在混合溶剂中,溶剂的微结构会发生变化,从而导致亲核试剂(如甲醇)的净保留。二恶烷-甲醇是一个例外,它可以提高转化率。分子力学计算表明,静电保留路径优先,但空间反转优先。激活参数指示反演和保留路径的负熵。A 2反应。