The Trepobatinae (Gerridae) of New Guinea and surrounding regions, with a review of the world fauna. Part 6. Phylogeny, biogeography, world checklist, bibliography and final taxonomic addenda
SuperQuat 5,5-dimethyl-4-iso-propyloxazolidin-2-one as a mimic of Evans 4-tert-butyloxazolidin-2-one
作者:Steven D. Bull、Stephen G. Davies、A. Christopher Garner、Dennis Kruchinin、Min-Suk Key、Paul M. Roberts、Edward D. Savory、Andrew D. Smith、James E. Thomson
DOI:10.1039/b605244d
日期:——
The incorporation of a gem-dimethyl group at the 5-position of a chiral oxazolidinone biases the conformation of the adjacent C(4)-stereodirecting group such that the gem-dimethyl-4-iso-propyl combination mimics a C(4)-tert-butyl group, providing higher levels of stereocontrol than a simple 4-iso-propyloxazolidinone. The generality of this principle is demonstrated with applications in stereoselective enolate alkylations, kinetic resolutions, Diels–Alder cycloadditions and Pd-catalysed asymmetric acetalisation reactions.
Benzylic C–H Esterification with Limiting C–H Substrate Enabled by Photochemical Redox Buffering of the Cu Catalyst
作者:Dung L. Golden、Chaofeng Zhang、Si-Jie Chen、Aristidis Vasilopoulos、Ilia A. Guzei、Shannon S. Stahl
DOI:10.1021/jacs.3c01662
日期:2023.5.3
Copper-catalyzed radical-relay reactions provide a versatile strategy for selective C–H functionalization; however, reactions with peroxide-based oxidants often require excess C–H substrate. Here, we report a photochemical strategy to overcome this limitation by using a Cu/2,2′-biquinoline catalyst that supports benzylic C–H esterification with limiting C–H substrate. Mechanistic studies indicate that
铜催化的自由基中继反应为选择性 C-H 官能化提供了一种通用策略;然而,与过氧化物基氧化剂的反应通常需要过量的 C-H 底物。在这里,我们报告了一种光化学策略,通过使用 Cu/2,2'-联喹啉催化剂来克服这一限制,该催化剂支持限制 C-H 底物的苄基 C-H 酯化反应。机理研究表明,蓝光照射促进羧酸盐到铜的电荷转移,将静止态 Cu II还原为 Cu I,从而激活过氧化物以生成烷氧基自由基氢原子转移物质。这种“光化学氧化还原缓冲”引入了一种独特的策略来维持自由基接力反应中铜催化剂的活性。
Remarkably Fast Acylation of Alcohols with Benzoyl Chloride Promoted by TMEDA