Isobutyryl chloride → HCID 178454485, compound

Participants

Reaction Steps

To a stirred solution of 2-(4-amino-1H-pyrazol-3-yl)-1H-benzoimidazole-5-carboxylic acid methyl ester [200 mg, Example 233(k)] in tetrahydrofuran (5 ml) was added diisopropylethylamine (545 μl) and isobutyryl chloride (327 μl) dropwise and the reaction stirred for 30 minutes. The reaction mixture was concentrated in vacuo and the residue was taken up in 1M potassium hydroxide in tetrahydrofuran/methanol (1:3, v/v) (5 ml) and stirred for 1 hour. The reaction mixture was concentrated in vacuo and the residue was taken up in 1M sodium hydroxide in water/methanol (5 ml) and stirred for 1 hour. The solvent was removed in vacuo and the residue was partitioned between ethyl acetate and water and the layers separated. The aqueous layer was acidified to pH 3-4 with 5% citric acid solution, extracted with ethyl acetate and the organic layer washed with brine. The organic layer was then dried over magnesium sulfate, filtered and the filtrate concentrated in vacuo to give 2-(4-isobutyrylamino-1H-pyrazol-3-yl)-1H-benzoimidazole-5-carboxylic acid (140 mg) as a white solid. LC-MS (METHOD C): RT=2.87 minutes, 313.33 (M+H)+.

Provenance & Evidence