Toluene → 1,2-Dihydroquinazoline

Participants

Reaction Steps

To toluene (200 mL), 5-bromo-2-amino-benzylamine (9.5 g, 47.2 mmol) and trimethylbenzoic orthoester (8.2 g, 47.2 mmol) were added, followed by p-toulensulfonic acid (1.35 g, 7.1 mmol). The resulting suspension was stirred at reflux for 50 hours. The reaction mixture was cooled at r.t., diluted with AcOEt (150 mL), washed with saturated sodium bicarbonate, then with water. The organic layer was dried and concentrated to provide the intermediate dihydroquinazoline as a light brown solid (8.5 g; 63%). This intermediate is dissolved in DCM (20 mL) at r.t., then MnO2 (5.1 g) was added. The resulting mixture was stirred at r.t. for 48 hrs, then filtered on celite. The filtrate was concentrated to provide the title product as white solid (8.1 g, 95%). C14H9BrN2; MW: 285.15; MS m/z: 286 (M+1). 1H-NMR (300 MHz, d6-DMSO) ppm: 7.58-7.61 (m, 3H), 8.02 (d, 1H), 8.17 (dd, 1H), 8.49-8.56 (m, 3H), 9.70 (s, 1H).

Provenance & Evidence