An efficient and practical protocol for the enantioselective cobalt‐catalyzed hydrovinylation of vinylarenes with ethylene at low (1.2 bar) pressure has been developed. As precatalysts, stable [L2CoCl2] complexes are employed that are activated in situ with Et2AlCl. A modular chiral TADDOL‐derived phosphine–phosphite ligand was identified that allows the conversion of a broad spectrum of substrates
Heterodimerization of Olefins. 1. Hydrovinylation Reactions of Olefins That Are Amenable to Asymmetric Catalysis
作者:T. V. RajanBabu、Nobuyoshi Nomura、Jian Jin、Malay Nandi、Haengsoon Park、Xiufeng Sun
DOI:10.1021/jo035171b
日期:2003.10.1
counteranion (BARF or SbF6) in an enantioselective version of the Ni-catalyzed reaction raises the prospects of developing a practical route for the synthesis of 3-arylbutenes. Several pharmaceutically relevant compounds, including widely used 2-arylpropionic acids, can be synthesized from these key intermediates. This reaction appears to be quite general. Synthesis of several new 2-diphenylphosphino-1
通过对配体和抗衡离子作用的系统检查,发现了用于乙烯和各种功能化乙烯基芳烃的近定量和高度选择性共聚的新方案。在典型的反应中,在-56℃下,在[CH2Cl2]中,在[CH3Cl2]中分别存在0.0035当量的[(烯丙基)NiBr] 2,三苯膦和AgOTf,4-溴苯乙烯和乙烯进行共二聚,得到3-(4-溴苯基)-1 -丁烯的收率和选择性均> 98%。与[(烯丙基)PdX] 2的相应反应效率低下且选择性低,在鉴定出可行的系统之前可能需要进一步优化。产生可比的产率和选择性的另一有用方案涉及使用由2-二苯基膦基苯甲酸烯丙酯,Ni(COD)2和(C 6 F 5)3 B制备的单组分催化剂。识别手性半不稳定配体(例如,(R)-2-甲氧基-2'-二苯基膦基-1,1'-联萘基,MOP)与高度离解的抗衡阴离子(BARF或SbF6)之间的协同关系Ni催化的反应的发展提出了开发合成3-芳基丁烯的实用路线的前景。可以从这
Fine-Tuning Monophosphine Ligands for Enhanced Enantioselectivity. Influence of Chiral Hemilabile Pendant Groups
作者:Aibin Zhang、T. V. RajanBabu
DOI:10.1021/ol0495063
日期:2004.4.1
[reaction: see text] C(2)-Symmetric P-(2-X-aryl)-2,5-dialkylphospholanes (X = dioxolan-2-yl or dioxan-2-yl), designed on the basis of a working model for asymmetric induction, are effective ligands for the Ni(II)-catalyzed asymmetric hydrovinylation of styrenes. Excellent yields (>99%), selectivities for the desired 3-arylbutenes (>99%), high S/C ratios (>1200), and ee's (up to 91%) have been realized for a
Tunable Ligands for Asymmetric Catalysis: Readily Available Carbohydrate-Derived Diarylphosphinites Induce High Selectivity in the Hydrovinylation of Styrene Derivatives
作者:Haengsoon Park、T. V. RajanBabu
DOI:10.1021/ja0172013
日期:2002.2.1
Only a limited number of ligands have been successfully employed for the Ni-catalyzed asymmetrichydrovinylationreaction. Diarylphosphonites prepared from readily available carbohydrates in conjunction with a highly dissociated counterion ([3,5-(CF3)2-C6H3)4B]- or SbF6-) effect the hydrovinylation of 4-bromostyrene or 4-isobutylstyrene under ambient pressure of ethylene with the best overall selectivities
只有有限数量的配体已成功用于 Ni 催化的不对称氢乙烯基化反应。由易得的碳水化合物与高度离解的抗衡离子([3,5-(CF3)2-C6H3)4B]- 或 SbF6-)制备的二芳基亚膦酸酯在乙烯的环境压力下影响 4-溴苯乙烯或 4-异丁基苯乙烯的加氢乙烯基化迄今为止报道的这些重要底物的最佳整体选择性。在 2-芳基丙酸的原型合成中,3-(4-溴苯基)-1-丁烯(以 98% 的分离产率和 89% 的 ee 从 4-溴苯乙烯制备)已被 Ni-转化为 (R)-布洛芬催化与 i-BuMgBr 交叉偶联、臭氧分解和随后生成的醛的氧化。
Enantioselective hydrovinylation via asymmetric counteranion-directed ruthenium catalysis
作者:Gaoxi Jiang、Benjamin List
DOI:10.1039/c1cc12499d
日期:——
The first Ru-catalyzed enantioselective hydrovinylation has been realized by using an asymmetriccounteranion-directedcatalysis strategy. Styrene derivatives react with ethylene in excellent yields and promising enantioselectivity using this approach.