The asymmetric hydrogenation of 2,2,2-trifluoroacetophenones and aryl perfluoroalkyl ketones was developed using a unique, well-defined chloride-bridged dinuclear rhodium(III) complex bearing Josiphos-type diphosphine ligands. These complexes were prepared from [RhCl(cod)]2 , Josiphos ligands, and hydrochloric acid. As catalyst precursors, they allow for the efficient and enantioselective synthesis
The invention relates to compounds of formula (I) and to their use in treating or preventing an inflammatory disease or a disease associated with an undesirable immune response: wherein A, L, RA1, RA2, RCand RDare as defined herein.
Platinum-catalyzed enantioselective hydrogenation of aryl-substituted trifluoroacetophenones
作者:Matthias von Arx、Tamas Mallat、Alfons Baiker
DOI:10.1016/s0957-4166(01)00524-9
日期:2001.12
The hydrogenation of 2,2,2-trifluoroacetophenones with different aryl-substituents (CF(3), N(Me)(2) and Me) has been studied over Pt/Al(2)O(3) modified by cinchonidine, its hydrochloride or O-methyl cinchonidine. Electron-withdrawing groups increased and electron-releasing groups decreased the rate and enantioselectivity of these reactions, although steric effects (with m- or p-substituents) were also critical. The 92% e.e. achieved in the hydrogenation of 2,2,2-trifluoroacetophenone is the highest value obtained so far in this reaction using any heterogeneous catalyst system. (C) 2002 Elsevier Science Ltd. All rights reserved.