This compound has been obtained by two related ways: 1) The saponification of 2-(5-chloro-2-oxobenzothiazolin-3-yl)acetic acid methyl ester (I) with NaOH in methanol/water gives the corresponding free acid (II), which is condensed with piperazine (III) by means of TiCl4 in THF yielding the acyl piperazine (IV). The nitrosation of (IV) with isoamyl nitrite in dichloromethane affords the N-nitrosopiperazine (V), which is finally reduced with Zn and acetic acid to the target amino derivative. 2) The nitrosation of piperazine (III) with NaNO2 and acetic acid gives 1-nitrosopiperazine (VI), which is reduced with Zn and acetic acid to 1-aminopiperazine (VII). The reaction of (VII) with benzaldehyde affords 1-(benzylideneamino)piperazine (VIII), which is condensed with of 2-(5-chloro-2-oxobenzothiazolin-3-yl)acetic acid (II) by means of SOCl2 and triethylamine in dichloromethane yielding the acyl piperazine (IX). Finally, this compound is debenzylated with hydroxylamine and HCl in acetonitrile/water.

This compound has been obtained by two related ways: 1) The saponification of 2-(5-chloro-2-oxobenzothiazolin-3-yl)acetic acid methyl ester (I) with NaOH in methanol/water gives the corresponding free acid (II), which is condensed with piperazine (III) by means of TiCl4 in THF yielding the acyl piperazine (IV). The nitrosation of (IV) with isoamyl nitrite in dichloromethane affords the N-nitrosopiperazine (V), which is finally reduced with Zn and acetic acid to the target amino derivative. 2) The nitrosation of piperazine (III) with NaNO2 and acetic acid gives 1-nitrosopiperazine (VI), which is reduced with Zn and acetic acid to 1-aminopiperazine (VII). The reaction of (VII) with benzaldehyde affords 1-(benzylideneamino)piperazine (VIII), which is condensed with of 2-(5-chloro-2-oxobenzothiazolin-3-yl)acetic acid (II) by means of SOCl2 and triethylamine in dichloromethane yielding the acyl piperazine (IX). Finally, this compound is debenzylated with hydroxylamine and HCl in acetonitrile/water.