N6-((4-Fluorophenyl)methyl)-3-nitropyridine-2,6-diamine → N~6~-[(4-Fluorophenyl)methyl]pyridine-2,3,6-triamine

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Reaction Steps

2-amino-3-nitro-6-(4-fluorobenzylamino)pyridine (ANFP) is dissolved in 2-methoxyethanol and is hydrogenated with hydrogen in the presence of Raney nickel at 5 bar and 60° C. to give 2,3-diamino-6-(4-fluorobenzyl-amino)pyridine. This is acylated with ethyl chloroformate and triethylamine under inert gas to give flupirtine base. The catalyst is filtered off and a solution of isopropanol and maleic acid is added directly to the filtrate which contains triethylamine hydrochloride, crude flupirtine maleate being precipitated with vigorous stirring under an inert-gas atmosphere.

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