Catalytic Parallel Kinetic Resolution under Homogeneous Conditions
作者:Trisha A. Duffey、James A. MacKay、Edwin Vedejs
DOI:10.1021/jo100695z
日期:2010.7.16
Two complementary chiral catalysts, the phosphine 8d and the DMAP-derived ent-23b, are used simultaneously to selectivelyactivate a mixture of two different achiral anhydrides as acyl donors under homogeneous conditions. The resulting activated intermediates 25 and 26 react with the racemic benzylic alcohol 5 to form enantioenriched esters (R)-24 and (S)-17 by fully catalyticparallelkinetic resolution
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。
Size-Driven Inversion of Selectivity in Esterification Reactions: Secondary Beat Primary Alcohols
作者:Stefanie Mayr、Marta Marin-Luna、Hendrik Zipse
DOI:10.1021/acs.joc.0c02848
日期:2021.2.19
alcohols carrying large aromatic side chains with anhydrides differing in size and electronic structure have been measured. While primary alcohols react faster than secondary ones in transformations with monosubstituted benzoic anhydridederivatives, relative reactivities are inverted in reactions with sterically biased 1-naphthyl anhydrides. Further analysis of reaction rates shows that increasing substrate
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