An Enantioselective Two-Component Catalyst System: Rh−Pd-Catalyzed Allylic Alkylation of Activated Nitriles
An Enantioselective Two-Component Catalyst System: Rh−Pd-Catalyzed Allylic Alkylation of Activated Nitriles
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DOI：
10.1021/ja954223e
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发表时间：
1996-04
影响因子：
15
通讯作者：
M. Sawamura;M. Sudoh;Y. Ito*
中科院分区：
文献类型：
--
作者：
M. Sawamura;M. Sudoh;Y. Ito*
本文报道了一种由两种不同的过渡金属配合物组成的双组分催化体系促进的新型对映选择性反应，已知活化的腈如R-氰基酯在催化量的低-CN-的影响下进行羟醛缩合和迈克尔反应，3价过渡金属配合物如RuH 2（PPh 3）4和RhH（CO）（PPh 3）3，1，并且我们报道了通过应用我们的反式螯合手性膦配体PhTRAP（1a）2与RhH（CO）（PPh 3）3或Rh（acac）（CO）2的组合，2-氰基丙酸酯和N-甲氧基-N-甲基-2-氰基丙酰胺的高度对映选择性Michael反应。3在我们实验室4和其他人1b，5中进行的机理研究表明，氰基丙酸酯被Rh-TRAP催化剂活化为通过氰基氮原子{trans-[Rh（NtCCMe-CO2 R）（CO）（PhTRAP）]}与铑原子配位的离域酯烯醇化物，烯醇化物中间体攻击不与金属配位的亲电体（迈克尔受体）。
We report here a novel enantioselective reaction promoted by a two-component catalyst system consisting of two different transition metal complexes, in which the two catalysts activate their respective substrates and the resulting active species react in an enantioselective manner to produce an optically active compound.Activated nitriles such as R-cyano esters are known to undergo aldol and Michael reactions under the influence of a catalytic amount of low-valent transition metal complexes such as RuH2 (PPh3) 4 and RhH (CO)(PPh3) 3, 1 and we reported the highly enantioselective Michael reaction of 2-cyanopropionates and N-methoxy-N-methyl-2-cyanopropionamide by applying our trans-chelating chiral phosphine ligand PhTRAP (1a) 2 in combination with RhH (CO)(PPh3) 3 or Rh (acac)(CO) 2. 3 Mechanistic studies carried out in our laboratory4 and others1b, 5 indicated that cyanopropionate is activated by the Rh-TRAP catalyst as delocalized ester enolate coordinating to the rhodium atom through the cyano nitrogen atom {trans-[Rh (NtCCMe-CO2R)(CO)(PhTRAP)]} and that the enolate intermediate attacks an electrophile (Michael acceptor) free from coordination to the metal.