两种互补的手性催化剂,膦8d和 DMAP 衍生的ent - 23b,同时用于在均相条件下选择性活化作为酰基供体的两种不同非手性酸酐的混合物。所得活化中间体25和26与外消旋苯甲醇5反应,通过完全催化平行动力学拆分(PKR)形成对映体富集的酯( R ) -24和( S ) -17。对于 PKR 过程,芳酰基酯 ( R )- 24以近乎理想的对映选择性获得,但 ( S)- 17被大约污染。8% 的次要对映异构体 ( R ) -17来自第二个途径,通过形成混合酸酐27并在8d激活。
Copper-Catalyzed Alkoxycarbonylation of Alkanes with Alcohols
作者:Yahui Li、Changsheng Wang、Fengxiang Zhu、Zechao Wang、Pierre H. Dixneuf、Xiao-Feng Wu
DOI:10.1002/cssc.201601587
日期:2017.4.10
Esters are important chemicals widely used in various areas, and alkoxycarbonylation represents one of the most powerful tools for their synthesis. In this communication, a new copper‐catalyzed carbonylative procedure for the synthesis of aliphatic esters from cycloalkanes and alcohols was developed. Through direct activation of the C −H bond of alkanes and with alcohols as the nucleophiles, the desired
Herein, we report a distinctive photoredox/copper dual-catalyzed esterification of benzylic C–H bonds through the combination of photoredox-mediated hydrogen atom transfer and Cu(II)-mediated radical-polar crossover. This methodology demonstrates a high functional group tolerance (>40 examples) and moderate to good yields with structurally diverse benzylic C–H substrates. Notably, stoichiometric amounts