Condensation of 2-(dimethylamino)ethyl chloride hydrochloride (I) with methylamine gave trimethyl ethylenediamine (II), which was coupled with 3,4-dichlorophenylacetic acid (III) in the presence of DCC to afford amide (IV). Subsequent reduction of (IV) with aluminum hydride in THF provided the title diamine.

Hexahydroazepine (I) was coupled with N-Boc-glycine (II) by means of EDC and HOBt, and the resulting amide (III) was reduced with LiAlH4 to give diamine (IV). Subsequent coupling of (IV) with 3,4-dichlorophenylacetic acid (V) in the presence of DCC afforded amide (VI). Finally, reduction of (VI) with aluminum hydride in THF provided the title compound.

Diamine (II) was prepared by reaction of N-(2-chloroethyl)pyrrolidine hydrochloride (I) with ethylamine. Coupling of (II) with 3,4-dichlorophenylacetic acid (III) in the presence of DCC afforded amide (IV). The amide function of (IV) was finally reduced by means of aluminum hydride in THF to furnish the title diamine.