Ethyl cyanoacetate → 1-Ethyl-5-fluoro-6-(4-methyl-1-piperazinyl)-2-benzimidazoleacetonitrile

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Reaction Steps

1-[5-(Ethylamino)-2-fluoro-4-nitrophenyl]-4-methylpiperazine (2.8 g, 10 mmol) is dissolved in methanol (200 ml) and hydrogenated with 5 percent palladium/carbon under hydrogen at normal pressure. The palladium/carbon is filtered off and the filtrate is evaporated under reduced pressure. The residue is dried in a high vacuum, dissolved in diethyl glycol ethyl ether (10 ml) and then treated with ethyl cyanoacetate (2.26 g, 20 mmol). The solution is heated to 160° for 4 hours. The solvent is then distilled off and the residue is taken up in an acetic acid/ether mixture (100 ml, 1:2). The crystals obtained are filtered off, dissolved in an ethyl acetate/methanol mixture (6:4 and chromatographed on silica gel (eluent: ethyl acetate/methanol 6:4). The product is recrystallized from an ethyl acetate/acetonitrile mixture (9:1). There are obtained 1.17 g (39%) of 1-ethyl-5-fluoro-6-(4-methyl-1-piperazinyl)-2-benzimidazoleacetonitrile with a m.p. of 204°-206°.

Provenance & Evidence