Prochiral substrates (alkyl aryl ketones, cyclopropyl methyl ketone, 1-indanone, 1-tetralone, ethyl 2-oxo-4-phenylbutyrate, and N-(diphenylphosphinyl)acetophenoneimine) were subjected to asymmetric reduction with aluminum hydride reagents, which were prepared by modifications of NaAlH4 or AlH3 with chiral alpha,alpha,alpha',alpha'-tetraaryl-1,3-dioxolane-4,5-dimethanols (TADDOL). The effects of the nature of the substituents in TADDOL, the structure of the prochiral substrate, and the reaction conditions on the stereochemistry of reduction were investigated. The highest enantioselectivity (70-90% ee) was achieved upon reduction of alkyl aryl ketones and N-(diphenylphosphinyl)acetophenoneimine with NaAl(TADDOLate)H-2 in THF or diglyme at a temperature from -70 to -20 degreesC. The mechanism of asymmetric induction in the reduction reactions of ketones with aluminum hydride reagents is discussed. The stereochemical results of reduction were explained by comparing three-dimensional models of the most probable transition states.
Design and Evaluation of Inclusion Resolutions, Based on Readily Available Host Compounds
作者:Simona Müller、Marcel Cyrus Afraz、René de Gelder、Gerry J. A. Ariaans、Bernard Kaptein、Quirinus B. Broxterman、Alle Bruggink
DOI:10.1002/ejoc.200400613
日期:2005.3
of enantiomers through selective crystallisation of diastereomeric inclusioncompounds can extend the scope of traditional racemate resolution beyond salt forming compounds. To assess the practical value of this approach the literature was carefully screened and promising results were checked. Also an extensive range of new inclusion hosts suitable for resolution processes, derived from simple hydroxyand
PHOTOCHEMICAL METHODS OF MAKING CYCLOBUTANE BORONATES AND RELATED COMPOUNDS
申请人:Wisconsin Alumni Research Foundation
公开号:US20190040085A1
公开(公告)日:2019-02-07
The present technology relates generally cyclobutane boronates, including methods of preparation by exposing a mixture of a compound of Formula I in a solvent
and a catalytic amount of a visible light sensitizer to provide a compound of Formula II, stereoisomers thereof, and/or salts of any of the foregoing.
The cyclobutane boronate compounds are useful intermediates in the preparation of pharmaceutically active compounds as well as other other useful compounds.
Enantioselective Synthesis of Atropisomeric Vinyl Arene Compounds by Palladium Catalysis: A Carbene Strategy
作者:Jia Feng、Bin Li、Yun He、Zhenhua Gu
DOI:10.1002/anie.201509571
日期:2016.2.5
An efficient palladium‐catalyzed asymmetric synthesis of axially chiral vinylarenes from aryl bromides and hydrazones is reported. The products were easily oxidized to axially chiral biaryl compounds, and the phosphine oxides were readily reduced to phosphine ligands.
3‐dioxolane‐4,5‐dimethanol (TADDOL)‐based phosphoramidites has been synthesized and applied in the Ni‐catalyzed cycloisomerization of different dienes. Through the systematic variation of the three structural motifs of the lead structure, that is, the amine moiety, the protecting group, and the aryl substituents, the ligand features could be optimized for the asymmetriccycloisomerization of the model substrate
合成了基于α,α,α,α-四芳基-1,3-二氧戊环-4,5-二甲醇(TADDOL)的亚磷酰胺库,并将其用于Ni催化的不同二烯的环异构化。通过铅结构的三个结构基序(即胺部分,保护基和芳基取代基)的系统变化,可以优化配体特征,以使模型底物二烯丙基丙二酸二乙酯的不对称环异构化。新催化体系的底物范围已扩展到其他二烯丙基底物,包括不对称二烯。总体上具有高达13 500 h -1的极高活性,对五元外亚甲基亚环戊烷的选择性很高,对映选择性高达92% ee 已经实现。