phosphine–nickel complex and an axially chiral sodium dicarboxylate has been developed. The transformation features mild reaction conditions, a broad substrate scope, and excellent functional group tolerance, offering an efficient approach to an array of enantioenriched O-propargyl hydroxylamines. Mechanistic studies support the presumed role of the chiral carboxylate as a counterion for nickel catalysis enabling
已经开发了通过结合膦-镍络合物和轴向手性二羧酸钠催化的高度对映选择性的 O-炔丙基化。该转化具有温和的反应条件、广泛的底物范围和出色的官能团耐受性,为一系列富含对映体的O-炔丙基羟胺提供了一种有效的方法。机理研究支持手性羧酸盐作为镍催化的抗衡离子的假定作用,从而能够发现高度立体选择性的转化。该反应的威力通过其在强效萤火虫萤光素酶抑制剂和 ( S )-二氢yashabushiketol 的不对称全合成中的应用来说明。
Rh<sup>I</sup>, Ir<sup>III</sup> ,and Co<sup>III</sup> Complexes with Atropchiral Biaryl Cyclopentadienyl Ligands: Syntheses, Structures, and Catalytic Activities
作者:Coralie Duchemin、Gints Smits、Nicolai Cramer
DOI:10.1021/acs.organomet.9b00365
日期:2019.10.28
trimethylsilyl, I, and Br. We introduce as well Cpx ligands with a new atropchiral MeO-biphenyl backbone. All ligands are smoothly complexed with rhodium(I) salts. The CpxRhI complexes obtained were systematically mapped by X-ray crystal analysis in order to collect steric parameters that might guide a rational selection of the chiral Cpx ligand for enantioselective reactions. The catalytic performances
手性环戊二烯基(Cp x)9族金属络合物已成为用于多种有效对映选择性C–H官能化的通用催化剂。在3,3'-位置具有调节选项的从手性二萘并萘衍生的Cp x配体提供了可靠的催化剂选择,提供了高对映选择性和良好的反应性。在本文中,我们报告了在3,3'-位具有新取代基的三萘基骨架Cp x配体的简化合成:即三甲基甲硅烷基,I和Br。我们还引入了具有新的萎缩性MeO-联苯骨架的Cp x配体。所有配体均与铑(I)盐顺利络合。Cp x Rh I通过X射线晶体分析系统地绘制获得的配合物,以收集可能指导合理选择手性Cp x配体用于对映选择性反应的空间参数。通过两次Rh III催化的C–H官能化(作为基准转化)评估了配合物的催化性能。在这两种情况下,更容易接近配体都提供了出色的反应性和对映选择性。另外,制备并表征了配备有已开发的配体的相关的Cp x Co III和Cp x Ir III复合物。
A modular approach to a new class of phosphinohydrazones and their use in asymmetric allylic alkylation reactions
作者:Michael Widhalm、Michael Abraham、Vladimir B. Arion、Siret Saarsalu、Uno Maeorg
DOI:10.1016/j.tetasy.2010.05.031
日期:2010.8
A group of five phosphino hydrazones with a pendant binaphthyl unit as a chiral modifier has been synthesized from non-racemic 2,2'-bis(bromomethyl)-1,1'-binaphthyl and 3,3'-diiodo-2,2'-bis(bromomethyl)-1,1'-binaphthyl as the key intermediates. Their efficiency as chiral ligands in palladium-catalyzed allylic alkylation reactions has been investigated showing up to 95% ee under optimized conditions. X-ray diffraction structures of mono- and dimeric Pd complexes are also reported. (C) 2010 Elsevier Ltd. All rights reserved.