Asymmetric synthesis of axially chiral benzamides and anilides utilizing planar chiral arene chromium complexes
Asymmetric synthesis of axially chiral benzamides and anilides utilizing planar chiral arene chromium complexes
复制标题
DOI：
10.1016/j.tet.2004.01.096
复制
发表时间：
2004-05-10
期刊：
影响因子：
2.1
通讯作者：
Uemura, M
中科院分区：
文献类型：
--
作者：
Koide, H;Hata, T;Uemura, M
利用平面手性（芳烃）铬配合物立体选择性地合成了具有光学活性的轴手性2，6-二取代苯甲酰胺和苯甲酰苯胺。对映体纯的平面手性三羰基（N，N-二乙基-2-甲基-6-甲酰基-（或6-酰基）苯甲酰胺）铬配合物进行亲核加成反应，高选择性地合成了轴向手性2-甲基-6-取代N，N-二乙基苯甲酰胺铬配合物。用于制备轴向手性苯甲酰胺或苯胺的替代方法是在N，N-二乙基-2，6-二甲基苯甲酰胺和N-甲基-N-酰基-2，6-二甲基苯胺的前手性三羰基铬络合物的苄基甲基处用手性氨基锂进行对映体锂化，随后进行亲电取代。所得的轴向手性铬络合苯甲酰胺和苯甲酰苯胺在空气中氧化，得到无铬的轴向手性苯甲酰胺和苯甲酰苯胺，在对映体富集的形式，在室温下没有轴向键旋转。(C)2004爱思唯尔有限公司保留所有权利。
Optically active axially chiral 2,6-disubstituted benzamides and anilides were stereoselectively prepared by utilizing planar chiral (arene)chromium complexes. Nucleophilic addition to enantiomerically pure planar chiral tricarbonyl(N,N-diethyl-2-methyl-6-formyl- (or 6-acyl)benzamide)chromium complex gave axially chiral 2-methyl-6-substituted N,N-diethyl benzamide chromium complexes with high selectivity. An alternative method for the preparation of axial chiral benzamides or anilides is an enantiotopic lithiation at the benzylic methyl of prochiral tricarbonylchromium complexes of N,N-diethyl-2,6-dimethylbenzamide and N-methyl-N-acyl-2,6-dimethylaniline with a chiral lithium amide followed by electrophilic substitution. The resulting axially chiral chromium-complexed benzamides and anilides were oxidized in air to give chromium-free axially chiral benzamides and anilides in enantiomerically enriched form without axial bond rotation at room temperature. (C) 2004 Elsevier Ltd. All rights reserved.