Process for the preparation of the Z-isomer of 3-(4-bromophenyl)-N-methyl-3-(3-pyridyl)allylamine

The Z-isomer of 3-(4-bromophenyl)-N-methyl-3-(3-pyridyl)allylamine of the formula (I) or of one of its pharmaceutically acceptable acid addition salts acts as a strongly selective inhibitor of the neuronal uptake of 5-hydroxytryptamine and can be used as an antidepressant or neuroleptic. It is prepared by reacting a compound of the formula (IV) in which Y is a leaving group, with monomethylamine. The stereoisomer mixture obtained is recrystallised three times from ethanol in the form of its oxalate, in which the two E- and Z-isomers have a significantly different solubility. The pure Z-isomer is obtained. The synthesis is also carried out by starting from a starting material which is a pure Z-stereoisomer, the recrystallisation of the product of course being unnecessary.