Chemoenzymatic syntheses of (R)-2-bromo-, (R)2-chloro- and (R)2-azido-1-(1,3-benzodioxol-5-yl)-1-ethanol
摘要:
Enantioselective reductions of 2-X-1-(1,3-benzodioxol-5-yl)-1-ethanones, (X = Cl, Br, N-3) by Rhodothorula glutinis CCT 2182 afforded the corresponding (R)-ethanols in good to excellent yields (57-99%) and excellent enantiomeric excesses (>99%). These alcohols may be used as raw materials for the preparation of the pharmaceuticals (R)-(-)-epinephrine, (R)-(-)-norepinephrine and (R)-(-)-isoproterenol. (C) 2004 Elsevier Ltd. All rights reserved.
SELECTIVE PREPARATION OF α,α-DICHLOROKETONES WITH COPPER(II) CHLORIDE
作者:José Arimateia Nobrega、Simone Maria C. Gonçalves、Clovis Peppe
DOI:10.1081/scc-120015383
日期:2002.1.1
Aryl and enolizable alkyl ketones react with copper(H) chloride in dimethylformamide to produce the corresponding alpha,alpha-dichloroketone in high yields. Remarkable qualities of the process are high selectivity towards these substrates, undetected polychlorinated by-products, easy work-up, commercially available reagents and HCl as the only waste stream.
Chemoenzymatic syntheses of (R)-2-bromo-, (R)2-chloro- and (R)2-azido-1-(1,3-benzodioxol-5-yl)-1-ethanol
作者:Heidi Antunes、Lucı́dio C. Fardelone、J. Augusto R. Rodrigues、Paulo J.S. Moran
DOI:10.1016/j.tetasy.2004.07.029
日期:2004.9
Enantioselective reductions of 2-X-1-(1,3-benzodioxol-5-yl)-1-ethanones, (X = Cl, Br, N-3) by Rhodothorula glutinis CCT 2182 afforded the corresponding (R)-ethanols in good to excellent yields (57-99%) and excellent enantiomeric excesses (>99%). These alcohols may be used as raw materials for the preparation of the pharmaceuticals (R)-(-)-epinephrine, (R)-(-)-norepinephrine and (R)-(-)-isoproterenol. (C) 2004 Elsevier Ltd. All rights reserved.
Switching Over of the Chemoselectivity: I<sub>2</sub>-DMSO-Enabled α,α-Dichlorination of Functionalized Methyl Ketones
Precise control of the chemoselectivity of the halogenation of a substrate equipped with multiple nucleophilic sites is highly demanding and challenging. Most reported chlorinations of methyl ketones show poor compatibility or even exclusive selectivity toward electron-rich arene, olefin, and alkyne residues. This is attributed to the direct or in situ employment of electrophilic Cl2/Cl+ species. Here