O-Phenylenediamine → 3-(1H-benzimidazol-2-yl)-2(1H)-Quinolinone

Participants

Reaction Steps

A suspension of 2-oxo-1,2-dihydroquinoline-3-carboxylic acid 1-1 (500 mg, 2.64 mmol, 1 equiv, prepared by the method of Marsais, F; Godard, A.; Queguiner, G. J. Heterocyclic Chem. 1989, 26,1589) and 1,2-phenylenediamine (344 mg, 3.18 mmol, 1.20 equiv) in polyphosphoric acid (15 mL) was heated under argon at 200° C. for 4.5 h. The hot reaction mixture was poured over ice (200 g), and the resulting mixture was allowed to stand overnight (20 h). The precipitate was filtered, washed with water (200 mL), and air dried to give the title compound as an olive-colored solid. 1H NMR (400 MHz, (CD3)2SO) δ 12.58 (s, 1H), 9.15 (s, 1H), 7.94 (br d, 1H, J=7.5 Hz), 7.78 (dd, 2H, J=5.6, 2.9), 7.63 (br t, 1H, J=7.5 Hz), 7.42 (br d, 1H, J=8.2 Hz), 7.33 (dd, 2H, J=5.9, 2.9), 7.25 (br t, 1H, J=7.5 Hz); HRMS (electrospray FT/ICR) calculated for C16H12N3O [M+H]+ 262.0975, found 262.0981; anal. calcd for C16H11N3O+1.10 H3PO4+0.75 H2O: C, 50.23; H, 4.16; N, 10.98. Found C, 50.24; H, 4.21; N, 10.93.

Provenance & Evidence