Chinoin Gyogyszer Es Vegyeszeti Termekek Gyara Rt.

Maria Hima Nee Toth

Gyorgy Lugosi

Maria Bakonyi

Sandor Szoke

Maria Sziladi

Tibor Montai

Tamas Kallai

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,

Process for the preparation of benzimidazole-thiol

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.

Process for the preparation of

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Budapest, Hungary

Maria Hima Nee Toth