Methanol → 1-Phenyl-1H-imidazole-4-carboxylic acid

Participants

Reaction Steps

A stirred solution of 1H-imidazole-4-carboxylic acid (0.5 g, 0.00446 mmol), concentrated sulfuric acid (0.5 mL) and MeOH (20 mL) was heated to reflux overnight. The reaction mixture was concentrated under reduced pressure. The residue was diluted with cold water, extracted with ethyl acetate and washed the organic layer with sodium bicarbonate. The organic layer was dried over sodium sulfate and concentrated under reduced pressure to afford 325 mg (58% Yield) of 1H-imidazole-4-carboxylic acid methyl ester. A mixture of 1H-imidazole-4-carboxylic acid methyl ester (225 mg, 1.8 mmol), cuprous oxide (225 mg, 1.8 mmol), iodobenzene (736 mg, 3.6 mmol), 1,10-phenanthroline (320 mg, 1.8 mmol) and cesium carbonate (1.74 g, 5.3 mmol) in DMSO (2 mL) in a seal tube was subjected to reaction in a microwave reactor (time: 5 min, temp: 90° C., power: zero) The reaction mixture was filtered through celite and the filtrate collected was concentrated under reduced pressure. The residue was diluted with cold water, extracted with ethyl acetate, dried over sodium sulfate and concentrated under reduced pressure to afford the residue. Purification by column chromatography (using 60-120 silica gel and 50% ethyl acetate in hexane as eluent) to afford 200 mg (55% Yield) of 1-phenyl-1H-imidazole-4-carboxylic acid methyl ester. LiOH.H2O (143 mg, 3.4 mmol) was added to a stirred solution of 1-phenyl-1H-imidazole-4-carboxylic acid methyl ester (231 mg, 1.1 mmol) in a mixture of THF (3 mL), MeOH (1 mL), H2O (1 mL) and stirring was continued at ambient temperature for 3 hrs. The reaction mixture was concentrated under reduced pressure. Cold water was then added and acidified it with 10% aqueous HCl, the solid was collected to afford 180 mg (83.7% Yield) of 1-phenyl-1H-imidazole-4-carboxylic acid.

Provenance & Evidence