PROCESS FOR PREPARATION OF 3,24;16,22-DI-O,O-ISOPROPYLIDENEPROTOESCIGENIN AND CRYSTALLINE FORMS THEREOF

摘要

Process for preparation of 3,24;16,22-di-O,O-isopropylideneprotoescigenin comprises acetonidation of protoescigenin monohydrate in the mixture consisting of 0 - 100% vol. of acetone and 100 - 0% vol. of 2,2-dimethoxypropane, in presence of catalytic amount of an acid, furnishing precipitation of the crystalline product from the reaction mixture. 3,24; 16,22 -Di-O,O- isopropylideneprotoescigenin is isolated either in crystalline form A or B.