O-Phenylenediamine → 3-(1H-Benzoimidazol-2-yl)-1H-[1,8]naphthyridin-2-one

Participants

Reaction Conditions

Reaction Steps

A mixture of 5-3 (300 mg, 1.37 mmol, 1 equiv) and 1,2-phenylenediamine (223 mg, 2.06 mmol, 1.5 equiv) in polyphosphoric acid (8 mL) was heated at 200° C. for 16 h. The hot rxn mixture was poured into ice water (50 mL), and the resulting mixture was allowed to stand until all polyphosphoric acid had dissolved. The acidic suspension was neutralized with saturated aqueous sodium bicarbonate solution, then extracted with ethyl acetate (5×100 mL). The combined organic layers were dried over sodium sulfate and concentrated. The residue was suspended in ethyl acetate (50 mL) aided by sonication, and the solids were filtered to give 3-(1H-benzoimidazol-2-yl)-1H-[1,8]naphthyridin-2-one (5-4) as a yellow solid.

Provenance & Evidence