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。
Catalytic Enantioselective Reduction of Ketones by a Chiral Gallium Complex and Catecholborane
Noyori's famous BINAL reagent Li[AlH(OEt)(BINOL dianion)] is formed by the combination of LiGaH4 , monothiobinaphthol (MTB), and catecholborane. With this mixture unsymmetrical ketones can be reduced in high enantioselectively. Un=unsaturated unit; R=alkyl.
Diastereoselective Intermolecular Cyclopropanation of Simple Alkenes by Fischer Alkenyl and Heteroaryl Carbene Complexes of Chromium: Scope and Limitations
作者:José Barluenga、Salomé López、Andrés A. Trabanco、Alvaro Fernández-Acebes、Josefa Flórez
DOI:10.1021/ja000694b
日期:2000.8.1
The intermolecular cyclopropanation of simple alkyl-substituted alkenes with Fischer methoxycarbene complexes under thermal conditions is reported. The scope and limitations of this [2 + 1] cycloaddition with respect to the nature of the carbene complex, substitution pattern of the electron neutral olefin, and functional group tolerance in the electron neutral olefin are described in detail. This methodology
Dimethylaluminum methaneselenolate—a useful reagent for the preparation of selenoesters. A new friedel-crafts acylation procedure promoted by Cu(I)
作者:Alan P. Kozikowski、Anthony Ames
DOI:10.1016/s0040-4020(01)96721-3
日期:1985.1
The preparation of a new aluminum reagent, dmiethylaluminum methaneselenolate (Me2AlSeMe) is described. The reactivity of this aluminum reagent toward a variety of organic substrates has been studied. Me2AlSeMe will convert O-alkyl esters to selenoesters in high yield. These selenoesters function as extremely reactive acyl transfer agents and are converted to acids, esters, and amides on reaction with
2-Acylfuran derivatives ##STR1## (R: alkyl, phenyl, etc.; R.sub.1 : H, alkyl) are prepared in high yield by reaction, in the presence of a boron trifluoride complex catalyst, of a furan compound ##STR2## (X: H, Cl, Br; Y: Cl, Br) or with RCOOH in the presence of (XYCHCO).sub.2 O.