Process for the preparation of high purity 1-(3-chlorophenyl)-4-methyl-7,8-dimethoxy-5H-2,3-benzodiazepine

摘要

According to an aspect of the invention there is provided for a process for the preparation of 1-[3'-(chloro)-phenyl]-4-[methyl[-7,8-di-[methoxy]-5H-2,3-benzodiazepine of formula CHEM in high purity and in a quality suitable for pharmaceutical purposes by reacting 1 mole of 2-(acetonyl)-3'-(chloro)-4,5-di-(methoxy)-benzophenone of formula CHEM with 3 to 7 moles of hydrazine hydrate in an organic solvent or in a mixture of organic solvents, at a temperature from 15 DEG C to 85 DEG C, and subsequently recrystallizing the crude product from an aliphatic alcohol containing 1 to 5 carbon atom(s), which is carried out in the absence of air oxygen. According to another aspect of the invention there is provided for a process for preparing purified 1-[3'-(chloro)-phenyl]-4-[methyl]-7,8-di-[methoxy]-5H-2,3-benzodiazepine of formula I from such containing contamination(s) of formula CHEM and/or particularly formula CHEM in which first the contaminated 1-[3'-(chloro)-phenyl]-4-[methyl]-7,8-di-[methoxy]-5H-2,3-benzodiazepine of formula I is treated with a solvent and an alkali hydroxide, alkali carbonate or alkali alcoholate and thereafter the compound 1-[3'-(chloro)-phenyl]-4-[methyl]-7,8-di-[methoxy]-5H-2,3-benzodiazepine of formula I is crystallized from the obtained solution.