10017-06-8Relevant articles and documents
Stereoselective synthesis of thienyl and furyl analogues of ephedrine
Effenberger, Franz,Eichhorn, Joachim
, p. 469 - 476 (1997)
The stereoselective syntheses of thienyl and furyl analogues of ephedrine starting from (R)- and (S)-cyanohydrins, respectively, are described. Addition of methyl Grignard to the O-trimethylsilyl protected optically active cyanohydrins (R)- and (S)-3 and hydrogenation of the resulting imino intermediates gives the erythro-2-amino alcohols 4 with high diastereoselectivity. Their reductive methylation leads to the enantiomerically pure thiophene analogues (1S,2S)- and (1R,2R)-6a, (1R,2S)- and (1S,2R)-6b as well as to the furan analogues (1S,2S)-6c and (1R,2S)-6d of ephedrine, The biological activity of the new compounds is under investigation.
Purification and characterization of a novel (R)-hydroxynitrile lyase from Eriobotrya japonica (Loquat)
Ueatrongchit, Techawaree,Kayo, Ai,Komeda, Hidenobu,Asano, Yasuhisa,H-Kittikun, Aran
, p. 1513 - 1522 (2008/12/21)
A hydroxynitrile lyase was isolated and purified to homogeneity from seeds of Eriobotrya japonica (loquat). The final yield, of 36% with 49-fold purification, was obtained by 30-80% (NH4)2SO4 fractionation and column chromatography on DEAE-Toyopearl and Concanavalin A Sepharose 4B, which suggested the presence of a carbohydrate side chain. The purified enzyme was a monomer with a molecular mass of 72 kDa as determined by gel filtration, and 62.3 kDa as determined by SDS-gel electrophoresis. The N-terminal sequence is reported. The enzyme was a flavoprotein containing FAD as a prosthetic group, and it exhibited a Km of 161 μM and a k cat/Km of 348 s-1 mM-1 for mandelonitrile. The optimum pH and temperature were pH 5.5 and 40°C respectively. The enzyme showed excellent stability with regard to pH and temperature. Metal ions were not required for its activity, while activity was significantly inhibited by CuSO4, HgCl2, AgNO3, FeCl3, β-mercaptoethanol, iodoacetic acid, phenylmethylsulfonylfluoride, and diethylpyrocarbonate. The specificity constant (kcat/Km) of the enzyme was investigated for the first time using various aldehydes as substrates. The enzyme was active toward aromatic and aliphatic aldehydes, and showed a preference for smaller substrates over bulky one.
Preparation of optically active cyanohydrins using the (S)-hydroxynitrile lyase from Hevea brasiliensis
Schmidt, Michael,Herve, Stephanie,Klempier, Norbert,Griengl, Herfried
, p. 7833 - 7840 (2007/10/03)
Several aliphatic, aromatic and heteroaromatic aldehydes have been converted into the chiral cyanohydrins using the (S) hydroxynitrile lyase from Hevea brasiliensis. The corresponding cyanohydrins were obtained in moderate to good yield and high enantiomeric excess with the exeption of phenyloxyacetaldehyde, benzyloxyacetaldehyde and the pyrrole-, pyridine- and indolealdehydes investigated. In contrast to previously reported results, cinnamaldehyde could be converted into (S)-(-)-2-hydroxy-4-phenyl-(E)-but-3- enenitrile with good selectivity by means of optimized reaction conditions.