Asymmetric hydrogenation of indene carboxylic acids: stereochemistry of hydrogen addition

被引：15

作者：

Borszeky, K ^{[1
]}

Mallat, T ^{[1
]}

Baiker, A ^{[1
]}

机构：

[1] ETH Zentrum, Tech Chem Lab, CH-8092 Zurich, Switzerland

来源：

TETRAHEDRON-ASYMMETRY | 1999年 / 10卷 / 24期

关键词：

D O I：

10.1016/S0957-4166(99)00576-5

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

The stereochemistry of hydrogen addition to cr,B-unsaturated carboxylic acids was studied by means of hydrogenation of indene carboxylic acids and their derivatives. Experiments were carried out over Pd/Al2O3 in the presence and absence of cinchonidine as a chiral modifier. In all cases hydrogenation occurred via bottom side syn addition of two hydrogen atoms to the chemisorbed substrate. Formation of trans isomers, up to 72%, was observed due to C=C bond isomerization in the substrate, and to adsorption and hydrogenation of the unsaturated molecule in a sterically unfavourable position. Adsorption in 'upside down' position was promoted by N-bases. Hydrogenation of 3-methylindene-2-carboxylic acid provided up to 45 % ee. Due to the high activity of Pd in C = C bond migration, a good ee can be achieved only when isomerization is negligible. (C) 2000 Elsevier Science Ltd. All rights reserved.

引用

页码：4781 / 4789

页数：9

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