Treatment of endo-2 or exo-2-hydroxy-1-substituted ketals 1a–d with p-toluensulfonic acid in dry benzene results in a reversible C9 bridge cleavage and affords equilibrium mixtures where 2-substituted-6-(1,3-dioxolan-2-yl)cyclooctanones 6a–d are present as main products. Yields in 6a–d are present as the steric hindrance of the substituents at C1 in the substrate increases as well. Deuterium exchange
用
对甲苯磺酸在干苯中处理内-2或外-2-羟基-1取代的
缩酮1a – d导致可逆的C 9桥裂解,并提供平衡混合物,其中2取代的6-(1,3 -二
氧戊环-2-基)
环辛酮6a - d是主要产物。随着底物C 1处取代基的空间位阻的增加,存在6a - d的产率。
氘交换实验有利于分子内1,3-
氢化物从C 2转变为C 9。