Abstract: A new process is disclosed for preparing a compound of the formula (I) ##STR1## wherein R is C.sub.1 to C.sub.5 alkyl; which comprises reducing a compound of the formula (II) ##STR2## or salt thereof wherein A is --SO.sub.2 X, --SOH, --SOA.sup.1, or --SA.sup.1 group,X is chlorine or hydrogen; andA.sup.1 is a group of the Formula ##STR3## with the aid of aluminum activated with a catalytic amount of a metal and/or metal salt in a mixture of water, a mineral acid, and an aliphatic carboxylic acid having 1 to 3 carbon atoms at a temperature of 0.degree. to 100.degree. C., thereafter, optionally, the product is recovered from an acid medium at a pH range of 2 to 3 in crystalline form.

Abstract: 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.