The reaction of pyridine-3-carbaldehyde (I) with KCN in HOAc/water gives the cyanohydrine (II), which is treated with NH4Cl and NH3 in water to yield 2-amino-2-(3-pyridyl)acetonitrile (III). The cyclization of (III) with S2Cl2 in DMF affords 3-chloro-4-(3-pyridyl)-1,2,5-thiadiazole (IV), which is condensed with tetraethyleneglycol (V) by means of NaH in THF to provide the disubstituted tetraethyleneglycol (VI). The methylation of the pyridine rings of (VI) with methyl iodide in acetone gives the bis N-methylpyridinium derivative (VII), which is finally selectively reduced with NaBH4 in methanol and treated with HCl in the same solvent to furnish the target bis-tetrahydropyridine compound, isolated as the dihydrochloride salt.

The reaction of pyridine-3-carbaldehyde (I) with KCN in HOAc/water gives the cyanohydrine (II), which is treated with NH4Cl and NH3 in water to yield 2-amino-2-(3-pyridyl)acetonitrile (III). The cyclization of (III) with S2Cl2 in DMF affords 3-chloro-4-(3-pyridyl)-1,2,5-thiadiazole (IV), which is condensed with tetraethyleneglycol (V) by means of NaH in THF to provide the disubstituted tetraethyleneglycol (VI). The methylation of the pyridine rings of (VI) with methyl iodide in acetone gives the bis N-methylpyridinium derivative (VII), which is finally selectively reduced with NaBH4 in methanol and treated with HCl in the same solvent to furnish the target bis-tetrahydropyridine compound, isolated as the dihydrochloride salt.