Process for the preparation of 6-demethyl-6-deoxy-6-methylene-5-oxytetracyclin and the 11A-chloro-derivative thereof

摘要

The invention relates to a new and improved process for the preparation of 6-demethyl-6-deoxy-6-methylene-5-oxytetracycline and the 11a-chloro derivative thereof by dehydrating 11a-chloro-5-oxytetracycline-6,12-hemiketal, which comprises treating 11a-chloro-5-oxytetracycline-6,12-hemiketal or an acid salt thereof with a dehydrating mixture formed by the reaction of chloro sulfonic acid and formic acid and isolating the 11a-chloro-6-demethyl-6-deoxy-6-methylene-5-oxytetracycline and salt thus obtained and optionally dehalogenating the same by reaction with a reducing agent. The advantage of the process of the present invention is that it is simple, economical and suitable for industrial scale manufacture and provides a pure product of high quality by excellent yields.