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Asymmetric hydrocyanation of aldehydes was accomplished using almond meal, containing the enzyme oxynitrilase. Optically active cyanohydrins with high levels of enantiomeric purity were obtained following a simple procedure. 相似文献
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This paper describes the stereoselective outcome of the intramolecular Diels-Alder furan (IMDAF) reaction of substituted (2S,3S)-ethanolamides 9-13, which were synthesised from a furyl substituted cyanohydrin. The latter was obtained from 2-furaldehyde with high enantioselectivity by an oxynitrilase catalysed addition of hydrogen cyanide. The stereochemistry of the IMDAF products was shown to be dependent on the size of the ethanolamide substituents R. Small substituents (H, Me, CN) gave exclusively exo-cycloaddition, whereas more bulky ones (Ph, Et) gave both evo- and endo-addition, the larger phenyl substituent giving a high endo-exo-ratio. 相似文献
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Rogier Brussee 《Mathematische Zeitschrift》1990,205(1):551-565
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Petra DG Reek JN Handgraaf JW Meijer EJ Dierkes P Kamer PC Brussee J Schoemaker HE van Leeuwen PW 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(15):2818-2829
The enantioselective outcome of transfer hydrogenation reactions that are catalysed by ruthenium(II) amino alcohol complexes was studied by means of a systematically varied series of ligands. It was found that both the substituent at the 1-position in the 2-amino-1-alcohol ligand and the substituent at the amine functionality influence the enantioselectivity of the reaction to a large extent: enantioselectivities (ee values) of up to 95% were obtained for the reduction of acetophenone. The catalytic cycle of ruthenium(II) amino alcohol catalysed transfer hydrogenation was examined at the density functional theory level. The formation of a hydrogen bond between the carbonyl functionality of the substrate and the amine proton of the ligand, as well as the formation of an intramolecular H...H bond and a planar H-Ru-N-H moiety are crucially important for the reaction mechanism. The enantioselective outcome of the reaction can be illustrated with the aid of molecular modelling by the visualisation of the steric interactions between the ketone and the ligand backbone in the ruthenium(II) catalysts. 相似文献
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P. Zandbergen H. M. G. Willems G. A. van der Marel J. Brussee A. van der Gen 《合成通讯》2013,43(19):2781-2787
2-Phenoxypropene (2) was applied as a novel protective reagent of chiral alcohols, yielding 2-phenoxy-isopropyl (PIP) ethers. Introduction and cleavage of the protective group was achieved under mild conditions. 相似文献
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Rogier Brussee 《Inventiones Mathematicae》1993,114(1):219-229
Summary We will prove that every differentiably embedded sphere with self-intersection –1 in a simply connected algebraic surface withp
g
>0 is homologous to an algebraic class. If the surface has a minimal model with Picard number 1 or |K
min| contains a smooth curve, and eitherp
g
orK
min
2
is even, then every such sphere is homologous to a (–1)-curve, as conjectured by Friedman and Morgan.Oblatum 15-IV-1993Supported by Nederlandse organisatie voor wetenschappelijk onderzoek NWO, stipend 04-63. 相似文献
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Erwin G. J. C. Warmerdam Johannes Brussee Arne van der Gen Chris G. Kruse 《Helvetica chimica acta》1994,77(1):252-256
The (R)- and (S)-5-(hydroxymethyl)-3-isopropyloxazolidin-2-ones, ((R)- and (S)- 2 , resp.), pivotal intermediates in the preparation of optically active β-blockers, were synthesized using (R,E)-2-hydroxypent-3-enenitrile ( 1 ) as the chiral starting material. In the synthesis of (R)- 2 , a known cyclization/inversion step was applied. 相似文献
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