The invention relates to the synthesis of
donepezil hydrochloride. According to a published patent CN100436416 which relates to a synthesizing technology of
donepezil hydrochloride,
diethyl malonate is adopted as an initial material, and 5 steps of condensation, reduction, substitution, ring-closing, and
decarboxylation are adopted, such that
donepezil hydrochloride is obtained. The steps are complicated, and the total yield is not high. The invention aims at providing a
donepezil hydrochloride synthesizing technology employing 5,6-dimethoxy-2-(4-pyridyl)
methylene-indan-1-one as an initial material. The technical scheme of the invention comprises steps that: the
raw material is processed through hydrogenation, cooling, and
filtration; a
solvent glacial
acetic acid is removed by reduced-pressure
distillation; the obtained solution is processed through
neutralization and extraction; a filtrate is condensed, and is dissolved in
dichloromethane; the mixture is stirred, and
triethylamine and
benzyl chloride are dropped into the solution; the solution is cooled, the filtrate is condensed, and the obtained material is dissolved in
methanol; a
methanol solution of
hydrogen chloride is dropped into the solution, such that a salt is formed; and the solution is cooled, crystallized, filtered, and dried, such that
donepezil hydrochloride is obtained. The synthesizing technology provided by the invention is advantaged in short synthetic
route and improved total yield. With the technology, the
donepezil hydrochloride content is higher than 99%. The technology is suitable for industrialized productions.