Asymmetric Catalysis, 105. Stereoselective Hydrogenation of Folic Acid with Immobilized Optically Active Rhodium(I)/Diphosphane Catalysts
作者:
Henri Brunner,
Petra Bublak,
Martina Helget,
期刊:
Chemische Berichte
(WILEY Available online 1997)
卷期:
Volume 130,
issue 1
页码: 55-62
ISSN:0009-2940
年代: 1997
DOI:10.1002/cber.19971300109
出版商: WILEY‐VCH Verlag
关键词: Diastereoselective hydrogenation;Folic acid;Immobilized optically active rhodium(I)/diphosphane catalysts;Leucovorin;HPLC analysis of 5‐formyltetrahydrofolic acid derivatives
数据来源: WILEY
摘要:
AbstractFor the hydrogenation of the CN bonds in the pyrazine ring of the vitamin folic acid (1) optically active rhodium(I)/diphosphane complexes immobilized on supports such as silica gel or Al2O3were used. The reduction was carried out at 50 bar hydrogen pressure in an aqueous solution buffered to pH 7. Thus, 5,6,7,8‐tetrahydrofolic acid (2) was obtained which contains a new asymmetric center at C‐6 of the pterine system. Therefore, in combination with the (S) configuration of the naturalL‐glutamic acid part of the molecule two diastereomers with (6S,S) and (6R,S) configuration arise. The relatively unstable tetrahydrofolic acid (2) was converted into its 5‐formyl derivative folinic acid (4) by treatment with methyl formate/formic acid in a 5:1 mixture of DMSO/pyridine. The Ca salt of folinic acid (4) is the widely used drug leucovorin. The diastereomers were separated by silica gel HPLC. To the column bovine serum albumine (BSA) is covalently bound. With optically active rhodium(I)/diphosphane catalysts, immobilized on silica gel supports, a diastereoselectivity of up to 90% could be achieved in the hydrogenation of folic
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