- A recyclable chiral auxiliary for the asymmetric syntheses of α-aminonitriles and α-aminophosphinic derivatives
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Optically active α-aminonitriles and α-aminophosphinic derivatives have been prepared in high yield and high ee using an easy route by extending our previously developed method involving the following sequence: (i) stereoselective Strecker condensation of
- Rossi, Jean-Christophe,Marull, Marc,Larcher, Nicolas,Taillades, Jacques,Pascal, Robert,van der Lee, Arie,Gerbier, Phillipe
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p. 876 - 883
(2008/09/21)
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- Chemistry of Aziridinecarboxylic Acids, IV. - Enantioselective Hydration of Aziridine-2-carbonitrile
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Aziridine-2-carbonitrile rac-1 was hydrated enantioselectively in aqueous medium by using (2R,3R,5R)-(-)-5-(1-hydroxy-1-methylethyl)-2-methyl-3-oxocyclohexanecarbonitrile (2) as chiral catalyst.The ee value of the unreacted (S)-(-)-aziridine-2-carbonitril
- Jaehnisch, Klaus,Gruendemann, Egon,Kunath, Annamarie,Ramm, Matthias
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p. 881 - 884
(2007/10/02)
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- Influence of a Hydroalcoholic Solvent on the Enantioselectivity of α-Amino nitrile Hydration Catalysed by Chiral Ketones
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The enantioselective hydration of α-aminonitriles 1, RCH(CN)NH2 i; 1c: R = Ph> has been achieved in an alkaline hydroalcoholic medium in the presence of chiral ketonic catalysts.Of the different ketones used, (-)-(5R,3R,2R)-5-(methylethenyl)-3-cyano-2-methylcyclohexanone (8) gives rise to significant enantioselectivity D/kL = 2.1; T = 10 deg C; solvent, water-propan-2-ol (45:55,v/v)>.Although the structure of the catalyst could probably be improved, we show in this paper that the efficiency and especiallythe enantioselectivity of the catalyst are not only under steric control but also depend on the nature and composition of the hydroalcoholic solvent.Thus, for the three aminonitriles studied in the presence of the catalyst 8, the increase in percentage of propan-2-ol favours the hydration of the D α-aminonitrile as shown for the hydration of 1c for which the ratio kD/kL increases threefold when the percentage of propan-2-ol increases from 10 to 95percent.
- Lagriffoul, Pierre-Henri,Tadros, Ziad,Taillades, Jacques,Commeyras, Auguste
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p. 1279 - 1285
(2007/10/02)
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- Hydratation enantioselective d'α-aminonitriles en presence de catalyseurs cetoniques chiraux supportes
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Enantioselective hydration of α-aminonitriles with chiral ketonic immobilized catalyst.In a previous publication, we showed that the hydration of α-aminonitriles under basic aqueous conditions was efficiently catalyzed by a poly(N-acryloylpiperidin-4-one) crosslinked with 20percent N,N'-bisacryloylpiperazine.In this paper, we show that lowering the degree of crosslinking and diluting piperidone sites inside the polymeric matrix by copolymerisation with an inactive comonomer (N-acryloylmrpholine), decrease catalyst degradation and improve average reactivity ofcatalytic sites.The best results were obtained with a 5percent crosslinked resin containing 15percent piperidin-4-one sites.With the same proportions, we prepared a polymer-supported chiral ketone 14 which catalyzes the enantioselective hydration of α-aminobenzylacetonitrile. Key words: α-aminonitrile / α-aminoamide / enantioselective hydration / polamer-supported catalysis / ketonic resins
- Taillades, J,Garrel, L.,Lagriffoul, P. H.,Commeyras, A.
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p. 191 - 198
(2007/10/02)
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