3,4-Diaminotoluene → 3-(5-Methyl-benzoimidazol-2-yl)-quinolin-2-one

Participants

Reaction Conditions

Reaction Steps

A suspension of 2-oxo-1,2-dihydro-quinoline-3-carboxylic acid 1-1 (500 mg, 2.64 mmol, 1 equiv) and 3,4-diaminotoluene (646 mg, 5.29 mmol, 2.00 equiv) in polyphosphoric acid (10 mL) was heated under argon at 200° C. for 2 h. The hot reaction mixture was poured over ice (200 g), and the resulting mixture was allowed to stand until all polyphosphoric acid had dissolved. The precipitate was filtered, washed with water (200 mL), and air dried. The olive-colored solid was partitioned between aqueous sodium bicarbonate solution (200 mL) and ethyl acetate (200 mL). The organic layer was dried over sodium sulfate and concentrated to give 1-3 as a yellow solid. 1H NMR (300 MHz, CDCl3) major hydrogen-bonded rotational isomer: δ 15.20 (br s, 1H), 14.30 (br s, 1H), 9.18 (s, 1H), 7.77 (br d, 1H, J=7.6 Hz), 7.61 (br d, 1H, J=7.5 Hz), 7.60 (br t, 1H, J=7.5 Hz), 7.37 (br s, 1H), 7.36 (br d, 1H, J=7.5 Hz), 7.32 (br t, 1H, J=7.6), 7.14 (br d, 1H, J=8.2 Hz), 2.52 (s, 3H); HRMS (electrospray FT/ICR) calcd for C17H14N3O [M+H]+ 276.1131, found 276.1132; TLC (40% EtOAc in hexane) Rf=0.10.

Provenance & Evidence