The Palladium-Catalyzed Aerobic Kinetic Resolution of Secondary Alcohols: Reaction Development, Scope, and Applications
作者:Davidâ C. Ebner、Jeffreyâ T. Bagdanoff、Ericâ M. Ferreira、Ryanâ M. McFadden、Danielâ D. Caspi、Raissaâ M. Trend、Brianâ M. Stoltz
DOI:10.1002/chem.200902172
日期:2009.12.7
and tert‐butyl alcohol greatly enhances reaction rates, promoting rapid resolutions. The use of chloroform as solvent allows the use of ambient air as the terminal oxidant at 23 °C, resulting in enhanced catalyst selectivity. These improved reaction conditions have permitted the successful kineticresolution of benzylic, allylic, and cyclopropyl secondary alcohols to high enantiomeric excess with good‐to‐excellent
已经开发出第一个钯催化的仲醇对映选择性氧化反应,利用容易获得的二胺(-)-金雀花石作为手性配体,分子氧作为化学计量氧化剂。关于碱基和氢键供体作用的机制见解导致了对原始系统的一些改进。也就是说,碳酸铯和叔丁醇的添加大大提高了反应速率,促进了快速分辨率。使用氯仿作为溶剂允许在 23 °C 下使用环境空气作为终端氧化剂,从而提高催化剂选择性。这些改进的反应条件使得能够以良好至优异的选择性因子成功地将苄基、烯丙基和环丙基仲醇动力学拆分为高对映体过量。该催化剂体系也已应用于内消旋二醇的去对称化,提供高产率的对映体富集的羟基酮。
Ni-Catalyzed Reductive Coupling of Alkyl Acids with Unactivated <i>Tertiary</i> Alkyl and Glycosyl Halides
作者:Chenglong Zhao、Xiao Jia、Xuan Wang、Hegui Gong
DOI:10.1021/ja510653n
日期:2014.12.17
highlights Ni-catalyzed reductivecoupling of alkyl acids with alkyl halides, particularly sterically hindered unactivated tertiary alkyl bromides for the production of all carbon quaternary ketones. The reductive strategy is applicable to α-selective synthesis of saturated, fully oxygenated C-acyl glycosides through easy manipulations of the readily available sugar bromides and alkyl acids, avoiding otherwise
Cyclopropenation of Alkylidene Carbenes Derived from α-Silyl Ketones
作者:Jingwei Li、Chunrui Sun、Daesung Lee
DOI:10.1021/ja101998w
日期:2010.5.19
A new cyclopropanation reaction involving Calpha-Si bond insertion of alkylidene carbenes derived from alpha-silyl ketones has been developed. This unprecedented alkylidene carbene reactivity features excellent selectivity for insertion into Calpha-Si bonds rather than insertion into Cgamma-H bonds or addition to gamma,delta-double or -triple bonds. The selectivity trend clearly indicates that the
Metal-Catalyzed Rearrangement of Cyclopropenes to Allenes
作者:Jingwei Li、Chunrui Sun、Silviya Demerzhan、Daesung Lee
DOI:10.1021/ja204979r
日期:2011.8.24
A novel transition-metal-catalyzed rearrangement of silylated cyclopropenes to the corresponding allenes is described. The presence of both the trimethylsilylgroup on the cyclopropene and the platinum catalyst are crucial for this rearrangement.