Methyl 2-methylbenzimidazole-5-carboxylate hydrochloride → Methyl 2-methyl-4,5,6,7-tetrahydro-1H-benzo[d]imidazole-6-carboxylate

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Reaction Steps

In an autoclave 6.8 g (30 mmols) of methyl 2-methylbenzimidazole-5-carboxylate hydrochloride, 6.0 g of 5% palladium-barium sulfate and 140 ml of acetic acid were charged and hydrogenation was carried out at 80° C. for 115 hours under 60 atms with stirring. After cooling, 5% palladium-barium sulfate was filtered off and the filtrate was distilled off under reduced pressure. After 200 ml of water was added to the residue, 1 N sodium hydroxide solution was added to the mixture at 0° to 5° C. to adjust pH to 9 to 10 followed by extraction with ethyl acetate. The ethyl acetate layer was dried over anhydrous magnesium sulfate and the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography and eluted with methylene chloride-methanol (10 : 1) to give 0.70 g (12.0%) of methyl 2-methyl-4,5,6,7-tetrahydrobenzimidazole-5-carboxylate.

Provenance & Evidence