Process for the preparation of 14,15-dihydro 14 (b-hydroxy (3x 16x) -eburnamenina-14-carboxylate and its epimer 14.15 hydroxy- (3x 16x) -eburnamenina-14-carboxylate methyl

摘要

14,15-Dihydro 14 beta-hydroxy (3alpha, 16alpha)-eburnamine 14-carboxylic acid methyl ester (A) and its epimer (B), of formula (I), in which R is OH and R' is COOMe for (A), and R is COOMe and R' is OH for (B), are made by reacting salts of tabersonine or vincadifformine in suspension or soln. in alcohol such as methanol, by irradiation with a monochromatic light source in presence of a photo-sensitiser for over 24h to bring about oxidn. and re-grouping.