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。
Tunable phosphinite, phosphite and phosphoramidite ligands for the asymmetric hydrovinylation reactions
successfully employed for the Ni-catalyzed asymmetric hydrovinylation reaction. Diarylphosphinites, carrying β-acylamino groups prepared from readily available carbohydrates, in conjunction with highly dissociated counteranions [(3,5-(CF3)2C6H3]4B− or SbF6−}, effect the hydrovinylation of vinylarenes under ambient pressure of ethylene with high enantioselectivity. Nitrogen substituents such as –COCF3 and COPh
phosphoramidites are a promising class of ligands for nickel-catalyzed asymmetric hydrovinylation of vinyl arenes. Cooperative effects are operative when ligands with more than one element of chirality are used. Choosing the proper stereochemistry in each part of the modular ligand system leads to high chemoselectivities and excellent enantioselectivities up to 94%. Moreover, the catalysts derived from these
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.