rhodium(I) cation in a bidentate fashion at the (π-arene)-bound phosphorus atom and at the olefin moiety. The P-olefin chelate coordination of 3 constructs the effective chiral environment at the metal center, and thus, these rhodium complexes display high performances in various rhodium-catalyzed asymmetric 1,4- and 1,2-addition reactions with arylboron nucleophiles. The control experiments demonstrated
Base-Free Conditions for Rhodium-Catalyzed Asymmetric Arylation To Produce Stereochemically Labile α-Aryl Ketones
作者:Xiaowei Dou、Yixin Lu、Tamio Hayashi
DOI:10.1002/anie.201601709
日期:2016.6.1
The asymmetric arylation of 2,2‐dialkyl cyclopent‐4‐ene‐1,3‐diones with aryl boronic acids was found to be efficiently catalyzed by a chiral diene–rhodium μ‐chloro dimer, [RhCl((R)‐diene*)}2], in the absence of bases in toluene/H2O to give 2,2‐dialkyl 4‐aryl cyclopentane‐1,3‐diones in high yields with high enantioselectivity. Such compounds can not be obtained with high enantiomeric purity under the
发现2,2-二烷基环戊-4-烯-1,3-二酮与芳基硼酸的不对称芳构化可以通过手性二烯-铑μ-氯二聚体[RhCl((R)-二烯*)} 2 ],在甲苯/ H 2 O中不存在碱的情况下,以高收率和高对映选择性得到2,2-二烷基4-芳基环戊烷-1,3-二酮。在用于铑催化的不对称芳基化的标准基本条件下,无法以高对映体纯度获得此类化合物,因为α-芳基酮产品在基本条件下会发生外消旋作用。
Transition metal catalysts
申请人:Grutzmacher Hansjorg
公开号:US20070155974A1
公开(公告)日:2007-07-05
The present invention relates to stereoisomerically enriched phosphorus compounds, transition metal catalysts which can be prepared therefrom and their use in stereoselective catalytic processes, and also a process for preparing the stereoisomerically enriched phosphorus compounds.
reaction with various substrates. The most promising results in both reactions were achieved with ligands 11 and 15, which contain a chiral alkene/achiral P-unit or an achiral alkene/chiral P moiety, respectively, and where the metal is complexed on the exo side of the tropene skeleton. In contrast, ligands with an endo coordination mode showed only low (13) or no activity (12) in all of the 1,4-additions
托烷衍生的磷-烯烃杂化配体带有 P-单元(手性 BINOL 衍生单元/非手性 PPh2-单元)与托烯骨架(手性/非手性)的各种组合已被合成并用于 Cu 催化的共轭 1,4-二乙基锌与环烯酮的加成以及在 Rh 催化的苯基硼酸(Hayashi-Miyaura 反应)与环状和非环烯酮的 1,4-加成中。而在 Cu 催化的反应中,只获得了中等的产率和 ee 值(高达 49% ee),而在 Hayashi-Miyaura 反应中观察到高达 97% ee 与各种底物。两个反应中最有希望的结果是用配体 11 和 15 实现的,它们分别包含一个手性烯烃/手性 P 单元或一个非手性烯烃/手性 P 部分,并且金属络合在 tropene 骨架的外侧. 相比之下,具有内配位模式的配体在所有 1,4-添加中仅显示低活性 (13) 或无活性 (12)。NMR 和 ESI-MS 实验表明溶液中存在两种阳离子 [RhI(15)2]+
Rh-Catalyzed Asymmetric 1,4-Addition of Arylboronic Acids to α,β-Unsaturated Ketones with DIFLUORPHOS and SYNPHOS Analogues
electron-deficient DIFLUORPHOS and SYNPHOS analogues in the rhodium-catalyzedasymmetric conjugate addition of boronic acids to α,β-unsaturatedketones afford the 1,4-addition adducts in yields up to 92% and with 99% ee. Particularly, a Rh-catalyzed asymmetric1,4-addition of arylboronic acids to nonsubstituted maleimide substrates using the (R)-3,5-diCF3-SYNPHOS ligand is also reported. This protocol provides access