5-methyl-1H-pyrazole-3-carboxylic acid → 1-isopropyl-6-(5-methyl-1H-pyrazol-3-yl)-3,5-dihydro-1H-benzo[1,2-d;4,5-d']diimidazol-2-one

Participants

Reaction Steps

5-Methyl-1H-pyrazole-3-carboxylic acid (126 mg, 1 mmol) and 5,6-diamino-1-isopropyl-1,3-dihydro-benzoimidazol-2-one (206 mg, 1 mmol) were heated to 160° C. in a mixture of polyphosphoric acid (5 g) and phosphorus pentoxide (500 mg, 3.5 mmol) for 6 h. This mixture was poured on water (20 ml) and stirring continued until a precipitate formed. After filtration the crude product was suspended in water and neutralized by the addition of aqueous ammonia (25%). The precipitate was collected, washed with water and dried in vacuo. Purification was achieved by chromatography on silica (dichloromethane/methanol 95:5) yielding 1-isopropyl-6-(5-methyl-1H-pyrazol-3-yl)-3,5-dihydro-1H-benzo[1,2-d;4,5-d′]diimidazol-2-one as slightly yellow solid. Yield 36 mg (12%)

Provenance & Evidence