The invention discloses a preparation method of
pramipexole dihydrochloride. The preparation method comprises the following steps: 1) in an
organic solvent, by taking 2,6-diamido-4,5,6,7-tetrahydrobenzothiazole as a
raw material, adding a resolving agent, heating for
reflux and carrying out cooling, suction
filtration and alkalization to prepare (-)-(6s)-2,6-diamido-4,5,6,7-tetrahydrobenzothiazole; 2) in an ethyl
alcohol solution, carrying out reaction on (-)-(6s)-2,6-diamido-4,5,6,7-tetrahydrobenzothiazole and
propionic anhydride and heating for
reflux to prepare (-)-(6s)-2-amino-6-propionylamino-4,5,6,7-tetrahydrobenzothiazole; 3) carrying out reduction reaction on (-)-(6s)-2-amino-6-propionylamino-4,5,6,7-tetrahydrobenzothiazole in a methylbenzene solution by red aluminum, heating for
reflux and carrying out stirring and
crystallization to prepare
pramipexole; 4) dissolving the
pramipexole in an isopropanol solution, reacting with
hydrochloric acid after stirring and
crystallization and carrying out decompression and
drying to obtain
pramipexole dihydrochloride. The preparation method is low in requirements for reaction equipment; the prepared
pramipexole dihydrochloride is high in content, high in purity, high in
solubility, high in output and less in
impurity.