Hydrochloric Acid → 3-Methyl-5-phenyl-1,3-dihydro-benzo[e][1,4]diazepin-2-one

Participants

Reaction Steps

To a stirred solution of the benzophenone 109 (10.65 g, 29.38 mmol) in CHCl3 (400 mL) at rt, hydrogen chloride gas was added in slowly. After 20 min, the addition was stopped and the solution was stirred overnight at rt. The reaction mixture was washed with a saturated solution of sodium bicarbonate (2×50 mL) and water (2×50 mL). The organic layer was concentrated under reduced pressure. The residual oil was dissolved in methanol-water (2:1, 500 mL) and the pH was adjusted to 8.5 by the addition of aqueous sodium hydroxide (1 N). The reaction mixture was stirred for 10 h at rt. The solution was concentrated under reduced pressure and water (100 mL) was added. The solution was extracted with CH2Cl2 (3×100 mL) and concentrated under reduced pressure. The crude solid 110 was purified by recrystallization from methanol/water to provide 110 (6.10 g, 83%). mp 160-162° C.; IR (KBr, cm−1) 3215, 3059, 2974, 2932, 1681, 1574, 1478, 1445, 1372, 1321, 1242, 1160, 1131; 1H NMR (CDCl3) δ 9.65 (s, 1H), 7.54-7.13 (m, 9H), 3.78 (q, J=6.5 Hz, 1H), 1.78 (d, J=7.1 Hz, 3H); MS (EI) m/e (relative intensity) 250 (M+, 40), 249 (83), 234 (15), 209 (75), 208 (76), 207 (100), 180 (17), 152 (19) 103 (23), 77 (40); [α]26D=290.2 (c 0.78, EtOAc).

Provenance & Evidence