Chemo- and enantioselective hydrogenation of the activated keto group of fluorinated β-diketones

被引：38

作者：

Hess, R ^{[1
]}

Diezi, S ^{[1
]}

Mallat, T ^{[1
]}

Baiker, A ^{[1
]}

机构：

[1] ETH Honggerberg, Swiss Fed Inst Technol, Inst Chem & Bioengn, CH-8093 Zurich, Switzerland

来源：

TETRAHEDRON-ASYMMETRY | 2004年 / 15卷 / 02期

关键词：

D O I：

10.1016/j.tetasy.2003.10.043

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

A symmetric hydrogenation of the activated carbonyl group of 1,1,1-trifluoro-2,4-diketones was studied over Pt/Al2O3 modified by various chiral 1,2-aminoalcohols and amines. The best chiral modifiers were cinchonidine and O-methyl-cinchonidine, which enhanced the chemoselectivity above 99%. The ee varied in the range of 22-86% depending on the steric hindrance around the nonactivated carbonyl group of the substrate. In one case the ee inverted from (S)- to the (R)-enantiomer by simply increasing the solvent polarity. The different reactivities of the substrates are correlated with their adsorption strength and the keto-enol equilibration, as only the keto form of the 2-carbonyl group is assumed to react on the chirally modified Pt surface. (C) 2003 Elsevier Ltd. All rights reserved.

引用

页码：251 / 257

页数：7

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