Phosphorus oxychloride → 4-chloro-9H-pyrimido(4,5-b)indole

Participants

Reaction Steps

A suspension of 3H-pyrimido[4,5-b]indol-4(9H)-one (0.091 g, 0.491 mmol) in phosphorous oxychloride (8 mL) was refluxed under nitrogen for 24 hours. Phosphorous oxychloride was removed by evaporation and the residue was partitioned between water (20 mL) and chloroform (2×20 mL). The organic extracts were filtered through celite, dried (Na2SO4) and concentrated to give 4-chloro-9H-pyrimido[4,5-b]indole as a yellow solid (0.103 g, 0.50 mmol, quantitative). 1H NMR (500 MHz, CDCl3) δ 7.60 (1H, dd, J=8.8 Hz), 7.70 (1H, dd, J=8.8 Hz), 8.43 (1H, d, J=8 Hz), 8.52 (1H, d, J=8 Hz), 8.98 (1H, s); LC-MS (3) Rt: 5.59 min; m/z (ESI) 206, 204 [MH+].

Provenance & Evidence