Amezinium metilsulfate

Amezinium metilsulfate is a sympathomimetic drug used for the treatment of low blood pressure. It has multiple mechanisms, including stimulation of alpha and beta-1 receptors and inhibition of noradrenaline and tyramine uptake.

Synthesis

This antidepressant is made from 2-butyne-1,4-diol starting material with as an intermediate.
The halogenation of 2-butyne-1,4-diol with chlorine gives mucochloric acid. Treatment with phenylhydrazine gives 1-phenyl-4,5-dichloro-6-pyridazone. Addition of ammonia leads to chloridazon. Catalytic hydrogenation yields 5-amino-2-phenylpyridazin-3-one. Alkylation with dimethyl sulfate completes the synthesis of amezinium metisulfate.