Enzymes in organic synthesis: remarkable influence of a π system on the enantioselectivity in PPL catalysed monohydrolysis of 2-substituted 1,3-diacetoxypropanes.
The invention relates to a process for preparing a compound of formula (I):
wherein said process comprises hydrogenation of a compound of formula (II);
under alkaline conditions, wherein R represents hydrogen or a labile group capable of being converted to hydrogen. The invention also relates to intermediates used in said process, to the use of said intermediates in the preparation of pregabalin and to a process for resolving racemic compounds of formula (I).
Chemoenzymic preparation of asymmetrized tris(hydroxymethyl)methane (THYM*) and of asymmetrized bis(hydroxymethyl)acetaldehyde (BHYMA*) as new highly versatile chiral building blocks
作者:Giuseppe Guanti、Luca Banfi、Enrica Narisano
DOI:10.1021/jo00031a039
日期:1992.2
A series of asymmetrized tris(hydroxymethyl)methanes 2 and bis(hydroxymethyl)acetaldehydes 3 have been prepared in both enantiomeric forms through a chemoenzymatic methodology. The key step is the highly enantioselective PPL-catalyzed monohydrolysis of 2(E)-alkenyl-1,3-diacetoxypropanes 25-27. A careful study on the effect of unsaturations adjacent to the prochiral center in a series of 2-substituted 1,3-diacetoxypropanes has confirmed the suggested beneficial effect of a pi-system in that position but has also unveiled an unprecedented dramatic effect of double-bond configuration on enantioselectivity. A new empirical model for the interpretation of these and other results, based both on polarity and steric arguments, is proposed. This study provides a general protocol for the efficient synthesis of asymmetrized 1,3-propanediols bearing in position 2 saturated or unsaturated carbon chains.
Ruhemann; Cunnington, Journal of the Chemical Society, 1898, vol. 73, p. 1015
作者:Ruhemann、Cunnington
DOI:——
日期:——
[EN] CRYSTALLINE FORMS OF PREGABALIN<br/>[FR] FORMES CRISTALLINES DE LA PRÉGABALINE
申请人:CADILA HEALTHCARE LTD
公开号:WO2008062460A3
公开(公告)日:2009-01-15
[EN] The invention relates to crystalline 'forms of Pregabalin and their process o preparation. The invention also relates to a process for preparing 2-carbethoxy-5- methylhex-2-enoic acid ethyl ester, an important intermediat for synthesis of crystalline Pregabalin, having less than about, 1-2% 2-carbethoxy-5-methylhex-3-enoic acid ethyl ester. Moreover, the present invention provides an industrially applicable process for recovery of chiral reagent used for resolution of the (+) (-)Pregabalin; thereby to provide a cost effective and economical process for preparation of Pregabalin. [FR] L'invention concerne des formes cristallines de la prégabaline et leur procédé de préparation. L'invention concerne également un procédé de préparation de l'ester éthylique d'acide 2-carbéthoxy-5-méthylhex-2-énoïque, un intermédiaire important de la synthèse de la prégabaline cristalline, comportant moins d'environ 1 à 2 % d'ester éthylique d'acide 2-carbéthoxy-5-méthylhex-3-énoïque. En outre, la présente invention propose un procédé applicable à l'échelle industrielle de récupération du réactif chiral utilisé pour la décomposition de la prégabaline (±), proposant ainsi un processus rentable et de faible coût de préparation de la prégabaline.