The use of an enantiomerically pure amino alcohol, coupled to a transfer hydrogenation process, in the asymmetric catalysis of the reduction of ketones to alcohols, is described. The process works well for unfunctionalised ketones, affording e.e.s of up to 98%, and excellent conversions. We have recently extended, for the first time in this application, the scope of the methodology to the reductions of a-heteroatom substituted substrates, through the use of the appropriate protecting groups on each atom.
The Activation of Carboxylic Acids via Self-Assembly Asymmetric Organocatalysis: A Combined Experimental and Computational Investigation
作者:Mattia Riccardo Monaco、Daniele Fazzi、Nobuya Tsuji、Markus Leutzsch、Saihu Liao、Walter Thiel、Benjamin List
DOI:10.1021/jacs.6b09179
日期:2016.11.9
The heterodimerizing self-assembly between a phosphoric acid catalyst and a carboxylic acid has recently been established as a new activation mode in Brønsted acid catalysis. In this article, we present a comprehensive mechanistic investigation on this activation principle, which eventually led to its elucidation. Detailed studies are reported, including computational investigations on the supramolecular
磷酸催化剂和羧酸之间的异二聚化自组装最近已被确立为布朗斯台德酸催化中的一种新活化模式。在本文中,我们对该激活原理进行了全面的机理研究,最终对其进行了阐明。报告了详细的研究,包括对超分子异二聚体的计算研究、催化循环的动力学研究,以及通过 DFT 计算对过渡态进行彻底分析,以合理化催化剂结构 - 选择性关系。在这些研究的基础上,我们开发了外消旋环氧化物的动力学拆分,其具有高选择性(高达 s = 93),以高对映纯度提供未反应的环氧化物和相应的受保护的 1,2-二醇。而且,
Asymmetric Transfer Hydrogenation of α-Amino and α-Alkoxy Substituted Ketones
作者:Jennifer A. Kenny、Matthew J. Palmer、Athene R. C. Smith、Tim Walsgrove、Martin Wills
DOI:10.1055/s-1999-2906
日期:——
Through the use of appropriate protecting groups, the asymmetric transfer hydrogenation of ketones bearing heteroatoms at the α-position may be achieved in high yield and enantioselectivity.
通过使用适当的保护基团,可以高产率和高对映选择性地实现δ位含有杂原子的酮的不对称转移氢化。
Kinetic Resolution of 1,2-Diols Using Nitrogen-Tethered Bisimidazoline-Copper(I) Catalyzed Benzoylation
Nitrogen-tethered bisimidazoline (Nb-imidazoline) ligand was utilized in the Cu(I)-catalyzed benzoylation of 1,2-diols. With the assistance of i-Pr(2)NEt, the reaction of rac-1,2-diols with o-methylbenzoyl chloride was smoothly catalyzed by Nb-imidazoline-CuCl in CH(2)Cl(2) to give the corresponding o-methylbenzoylated secondary alcohols in tip to 79% ee.
Kinetic Resolution of Diols and Pyridyl Alcohols by Cu(II)(borabox)-Catalyzed Acylation
Boron-bridged bisoxazoline (borabox) ligands have been used in the copper(II)-catalyzed benzoylation of pyridyl alcohols and 1,2-diols. Efficient kinetic resolution of 1,2-diols was achieved using both borabox and bisoxazoline (box) ligands. Borabox ligands induced high selectivities in the benzoylation of suitable pyridyl alcohols, where they outperformed bisoxazolines. In addition, highly enantioselective Cu(II)(borabox)catalyzed benzoylation has been used for the synthesis of both enantiomers of a pyridyl alcohol.