'an improved process for preparation of neostigmine methylsulfate'

摘要

The invention provides a novel process for preparation of neostigmine methylsulfate (I) comprising synthesis of 3-dimethylamino phenol by a process of quateraization of 3-amino phenol with dimethyl sulfate and demethylation with ethanolamine, followed by further reaction with N,N-dimethylcarbamoyl chloride in presence of a catalyst and a base to give 3-[(dimethylamino)carbonyl-oxy]-N,N-dimethylaniline of formula (IV) which on subsequent treatment with dimethyl sulfate gave neostigmine methylsulfate having desired purity.