Reaction of 3,5-dibromopyridine (I) with sodium ethoxide gave 3-bromo-5-ethoxypyridine (II). Palladium-catalyzed coupling of bromopyridine (II) with 3-buten-1-ol (III) yielded the pyridinylbutenol (IV), which was further converted to tosylate (V). Displacement of the tosylate group of (V) with methylamine then gave amine (VI).
In a related method, 4-bromo-1-butene (VII) was reacted with methylamine to produce the secondary amine (VIII). After protection of (VIII) as the tert-butyl carbamate (IX), palladium-catalyzed coupling with 3-bromo-5-ethoxypyridine (II) furnished adduct (X). The N-Boc protecting group of (X) was then cleaved under acidic conditions to afford amine precursor (VI). The title hemigalactarate salt was finally prepared by treatment of amine (VI) with D-galactaric acid in aqueous ethanol.