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。
Constraints of Opsin Structure on the Ligand-binding Site: Studies with Ring-fused Retinals¶
chromophores provided a twisted C11–C12 double bond for the C12–C14 ring-fused analog and all relaxed double bonds with a highly twisted C10–C11 bond for the C11–C13 ring-fused analog. The structural model of the C11–C13 ring-fused analog chromophore showed a characteristic flip of the cyclohexenyl moiety toward transmembrane segments 3 and 4. The structural models suggested that hulatwist is a primary process
Photoredox‐Catalyzed Isomerization of Highly Substituted Allylic Alcohols by C−H Bond Activation
作者:Kai Guo、Zhongchao Zhang、Anding Li、Yuanhe Li、Jun Huang、Zhen Yang
DOI:10.1002/anie.202000743
日期:2020.7.6
Photoredox‐catalyzed isomerization of γ‐carbonyl‐substituted allylicalcohols to their corresponding carbonyl compounds was achieved for the first time by C−H bond activation. This catalytic redox‐neutral process resulted in the synthesis of 1,4‐dicarbonyl compounds. Notably, allylicalcohols bearing tetrasubstituted olefins can also be transformed into their corresponding carbonyl compounds. Density
We report a short and convenient synthesis of two configurationally locked retinals that are important for applications in the context of optogenetics. The C11–C15 cyclopentyl fragments of both retinals were obtained by palladium-catalysed alkoxycarbonylation and merged with the rest of the carbon skeleton through Wittig olefination. The preparation of the required and known ylide precursor was revisited