| 摘要 |
The invention relates to a process for the preparation of ginkgolide B by conversion of ginkgolide C into ginkgolide B, and to the ginkgolide B thus obtained, which is a potent inhibitor of PAF-acether. The process of the present invention comprises the steps of protecting the 10-hydroxy group of ginkgolide C by conversion to an alkyl ester, the reaction being effected in dimethylformamide at a temperature of from 15 to 50.degree.C for from 4 to 10 ho urs; activating the 7-hydroxy group of the resultant 10-protected ginkgolide C by conversion to a (R)thiocarbonyl ester, the activation being effected in basic conditions at a temperature of from 0 to 40.degree.C for from 1 to 24 hours; deoxygenating the 7-activated group in the resultant 10-protected 7-activated ginkgolide C by treating it with tributyltin hybride or tris (trimethylsilyl)silane, in an aprotic solvent, in the presence of a freeradical generator, the reaction being effected at a temperature of from 70 to 110.degree.C for from 15 minutes to 3 hours under inert atmosphere, and cleaving the protecting group from the 10-hydroxy group of the resultant 10-protected ginkgolide B.
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