Double Diastereoselective Approach to Chiral <i>syn</i>- and <i>anti</i>-1,3-Diol Analogues through Consecutive Catalytic Asymmetric Borylations
作者:Alba Pujol、Andrew Whiting
DOI:10.1021/acs.joc.7b00854
日期:2017.7.21
Homoallylic boronate carboxylate esters derived from unsaturated aldehydes via an imination, β-borylation, imine hydrolysis, and Wittig trapping sequence, were subjected to a second boryl addition to give 1,3-diborylated carboxylate esters. Control of the absolute and relative stereochemistry of the two new 1,3-stereogenic centers was achieved through: (1) direct chiral catalyst controlled asymmetric borylation
经由亚胺基化,β-硼化,亚胺水解和Wittig捕获序列衍生自不饱和醛的均烯丙基硼酸酯羧酸酯,进行第二次硼烷基加成,得到1,3-二硼酸酯化的羧酸酯。通过以下方法控制两个新的1,3-立体异构中心的绝对和相对立体化学:(1)直接手性催化剂控制高ee在不饱和亚胺上的第一个立体中心的不对称硼化;(2)使用手性催化剂的不饱和酯的双非对映选择性控制的硼酸酯化,大大克服了来自第一个手性硼烷基中心的导向作用,从而使差的(不匹配的)到良好的(匹配的)非对映控制。随后,