期刊
TETRAHEDRON-ASYMMETRY
卷 20, 期 4, 页码 425-429出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.tetasy.2009.02.026
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An efficient biocatalytic procedure to obtain chiral N,O-nucleoside derivatives consisting of a lipase-catalysed resolution of the corresponding racemates in organic solvent has been developed. Enantioselective esterification of thymine and cytosine derivatives, (+/-)-9a and (+/-)-9b, has been Investigated by comparing the efficiency of different lipases and acyl donors. Since esterification of (+/-)-9a and (+/-)-9b, Occurred with low enantioselectivity (E <= 14) in the presence of the lipases considered, for preparative purposes we resorted, with Success, to a double sequential kinetic resolution, using Lipozyme IM as the best catalyst. This approach enables LIS to obtain all the enantiomers with ee >= 95%. The absolute configuration of the new chiral N-acetyl cytosine derivative 9b was established by circular dichroism spectroscopy. (c) 2009 Elsevier Ltd. All rights reserved.
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