Synthesis of achiral, but unsymmetric, seven-membered rhodium(I)-chelates for hydrogenation in the chiral environment of alkyl polyglucoside micelles
摘要:
Chiral rhodium(I) chelates containing a seven-membered ring are well-known active catalysts for the asymmetric hydrogenation of amino acid precursors. A high conformational flexibility allows their enantioselectivity to be strongly influenced by modifiers. Now we show the nature of the counter-ions to have a large influence in apolar solvents. In addition, the presence of micelle forming alkyl polyglycosides as amphiphiles causes a remarkable increase in the enantiomeric excess (%ee). However, on achiral catalysts this enantioselectivity inducing effect scarcely exceeds the standard deviation for the gas chromatographic determination of the enantiomeric ratio. This is also true for the application of unsymmetric P,P'-ligands such as 3-phosphinopropyl-phosphinites or butane-1,4-diyl-bis(phosphines) carrying different P'-aryl groups, for which synthetic routes are given. (C) 2001 Elsevier Science B.V. All rights reserved.
Synthesis of achiral, but unsymmetric, seven-membered rhodium(I)-chelates for hydrogenation in the chiral environment of alkyl polyglucoside micelles
摘要:
Chiral rhodium(I) chelates containing a seven-membered ring are well-known active catalysts for the asymmetric hydrogenation of amino acid precursors. A high conformational flexibility allows their enantioselectivity to be strongly influenced by modifiers. Now we show the nature of the counter-ions to have a large influence in apolar solvents. In addition, the presence of micelle forming alkyl polyglycosides as amphiphiles causes a remarkable increase in the enantiomeric excess (%ee). However, on achiral catalysts this enantioselectivity inducing effect scarcely exceeds the standard deviation for the gas chromatographic determination of the enantiomeric ratio. This is also true for the application of unsymmetric P,P'-ligands such as 3-phosphinopropyl-phosphinites or butane-1,4-diyl-bis(phosphines) carrying different P'-aryl groups, for which synthetic routes are given. (C) 2001 Elsevier Science B.V. All rights reserved.
[EN] HYDROGENATION OF ESTERS OR CARBONYL GROUPS WITH PHOSPHINO-OXIDE BASED RUTHENIUM COMPLEXES<br/>[FR] HYDROGÉNATION DE GROUPES ESTER OU CARBONYLE AVEC DES COMPLEXES DE RUTHÉNIUM À BASE D'OXYDE DE PHOSPHINE
申请人:FIRMENICH & CIE
公开号:WO2010038209A1
公开(公告)日:2010-04-08
The present invention relates to the field of catalytic hydrogenation and, more particularly, to the use of specific ruthenium catalysts, or pre-catalysts, in hydrogenation processes for the reduction of ketones, aldehydes and esters or lactones into the corresponding alcohol or diol respectively. Said catalysts are ruthenium complexes comprising a ligand of the type (N-N) type and a ligand of the type (P-PO).
Synthesis of achiral, but unsymmetric, seven-membered rhodium(I)-chelates for hydrogenation in the chiral environment of alkyl polyglucoside micelles
Chiral rhodium(I) chelates containing a seven-membered ring are well-known active catalysts for the asymmetric hydrogenation of amino acid precursors. A high conformational flexibility allows their enantioselectivity to be strongly influenced by modifiers. Now we show the nature of the counter-ions to have a large influence in apolar solvents. In addition, the presence of micelle forming alkyl polyglycosides as amphiphiles causes a remarkable increase in the enantiomeric excess (%ee). However, on achiral catalysts this enantioselectivity inducing effect scarcely exceeds the standard deviation for the gas chromatographic determination of the enantiomeric ratio. This is also true for the application of unsymmetric P,P'-ligands such as 3-phosphinopropyl-phosphinites or butane-1,4-diyl-bis(phosphines) carrying different P'-aryl groups, for which synthetic routes are given. (C) 2001 Elsevier Science B.V. All rights reserved.