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。
Lewis Acid Catalyzed [1,3]-Sigmatropic Rearrangement of Vinyl Aziridines
作者:Matthew Brichacek、DongEun Lee、Jon T. Njardarson
DOI:10.1021/ol802123e
日期:2008.11.6
This paper details the copper-catalyzed ring expansion of vinyl aziridines to 3-pyrrolines. Broad substrate scope (24 examples) using tosyl- and phthalimide-protected vinyl aziridine substrates is observed. Cu(hfacac)2 was determined to be superior to all other catalysts tested.
Exo- and endo-6-hydroxy- and 6,7-epoxytropanes; Total synthesis of scopine, pseudoscopine, and nor-derivatives
作者:David E Justice、John R Malpass
DOI:10.1016/0040-4039(95)00836-2
日期:1995.6
Novel endo- 6,7-epoxy-8-azabicyclo[3.2.1]octanederivatives and the corresponding exo-analogues have been synthesized and show substantially different reactivity; the resistance of the exo-epoxides to ring opening during hydride reduction and catalytic hydrogenolysis is exploited in a total synthesis of scopine, pseudoscopine, and nor -derivatives.
Surfing π Clouds for Noncovalent Interactions: Arenes versus Alkenes
作者:Abil E. Aliev、Josephine R. T. Arendorf、Ilias Pavlakos、Rafael B. Moreno、Michael J. Porter、Henry S. Rzepa、William B. Motherwell
DOI:10.1002/anie.201409672
日期:2014.11.17
functional‐group interactions with an arene dominate over those with an alkene, and that a π‐facial intramolecular hydrogen bond from a hydroxy group to an arene is favored by approximately 1.2 kJ mol−1. The strongest interaction observed in this study was with the cyano group. Analysis of the series of groups CH2CH3, CHCH2, CCH, and CN shows a correlation between conformational free‐energy differences
Enantio- and diastereoselective transformations of cycloheptatriene to sugars and related products
作者:Carl R. Johnson、Adam Golebiowski、Darryl H. Steensma、Mark A. Scialdone
DOI:10.1021/jo00077a049
日期:1993.12
Both meso diastereomers of 6-[(tert-butyldimethylsilyl)oxy]-2-cycloheptene-1,4-diol, prepared from cycloheptatriene, have been enzymatically asymmetrized by conversion to monoacetates using Pseudomonas cepacia lipase in isopropenyl acetate. A study of protecting group manipulations, diastereoselective oxidations, and regioselective ring openings utilizing these enantiopure monacetates which results in the synthesis of all possible methyl 2,4-dideoxyhexopyranosides is described.