| abstract |
The invention relates to a method which permits, in particular, the preparation of a galanthamine of the formula, through a novel bromo-N-demethylgalanthamine of the formula and a novel bromogalanthammine of the formula. By the process, the compound of the formula is oxidized to the compound of the formula which is diastereoselectively selectively selected from L-Selektride to the new bromine-N-demethylgalanthamine of the formula without producing demonstrable amounts of epibromo-N-demethylgalanthamine. By methylation, the novel bromogalanthamine of formula (5) is obtained from which, by cleavage of bromine, (+/-) galanthamine of formula (6) is obtained. By precipitating as a chiral acid salt, in particular as tartrate, the enantiomers can be obtained in pure form. According to the reaction scheme, all steps yield high yields and pure products, so that the process can be applied in industrial scale production. |