Chiral Phosphoric Acid Catalyzed Highly Enantioselective Desymmetrization of 2-Substituted and 2,2-Disubstituted 1,3-Diols via Oxidative Cleavage of Benzylidene Acetals
作者:Shan-Shui Meng、Yong Liang、Kou-Sen Cao、Lufeng Zou、Xing-Bang Lin、Hui Yang、K. N. Houk、Wen-Hua Zheng
DOI:10.1021/ja507332x
日期:2014.9.3
A highly enantioselective catalytic protocol for the desymmetrization of a wide variety of 2-substituted and 2,2-disubstituted 1,3-diols is reported. This reaction proceeds through the formation of an "ortho ester" intermediate via oxidation of 1,3-diol benzylidene acetal by dimethyldioxirane (DMDO) and the subsequent proton transfer catalyzed by chiral phosphoric acid (CPA). The mechanism and origins
报告了一种用于对各种 2-取代和 2,2-二取代 1,3-二醇去对称化的高度对映选择性催化方案。该反应通过二甲基二环氧乙烷 (DMDO) 氧化 1,3-二醇亚苄基乙缩醛形成“原酸酯”中间体进行,随后手性磷酸 (CPA) 催化质子转移。使用 DFT 计算确定了该反应的对映选择性的机制和起源。DMDO 的氧化是限速的,磷酸显着加速质子转移;底物的亚苄基部分与 CPA 的 2,4,6-三异丙基之间的吸引力相互作用是高对映选择性的关键。