Triethylamine → 1-(3-Imino-2-oxopropyl)-3-pyridin-2-yl-1,3-dihydro-2H-benzimidazol-2-one

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of (2-oxo-3-pyridin-2-yl-2,3-dihydro-1H-benzimidazol-1-yl)acetic acid (144 mg, 0.535 mmol, described in Intermediate 16) in THF (5 mL) at −10° C. was added triethylamine (0.097 mL, 0.695 mmol), followed by isobutyl chloroformate (0.090 mL, 0.695 mmol) and the resulting mixture was stirred at −10° C. for 3 h. A cold solution of diazomethane (ca. 1.0 mmol) in Et2O (3 mL) was added, and stirring was continued for 16 h, allowing the mixture to warm slowly to ambient temperature. The mixture was cooled to −10° C. and a cold solution of diazomethane (ca. 1.5 mmol) in Et2O (5 mL) was added, and the resulting mixture was allowed to warm to ambient temperature and stirred for 3 h. The solvent was removed in vacuo and the residue was partitioned between Et2O (20 mL) and saturated aqueous NaHCO3 (10 mL). The aqueous layer was extracted further with Et2O (2×10 mL) and the combined organic layers were dried over Na2SO4, filtered, and concentrated under reduced pressure. The residue was triturated with MeOH to give a pale solid. This solid was further purified by silica gel chromatography, eluting with a gradient of hexane:EtOAc—100:0 to 50:50, to give the title compound. MS: m/z=266 (M−N).

Provenance & Evidence