Boron tribromide → 1-Chloro-6-hydroxy-4-methylphthalazine

Participants

Reaction Steps

A solution of 1-chloro-6-methoxy-4-methylphthalazine (7) (1.0 g, 4.8 mmol), 1.0 M boron tribromide (17.00 mmol) in dichloromethane (17 mL), and dichloromethane (50 mL) is stirred under argon at −78° C. for 0.5 h, at room temperature for 22 h, and at reflux for 4 h. After being cooled to room temperature, the mixture is diluted with H2O (100 mL) and sat. NaHCO3 (80 mL) and extracted with ethyl acetate (150 mL and 4×100 mL). The extract is washed (brine) and dried. Solvent is removed at reduced pressure to give 184 mg of an impure brown solid consisting of by-products. The aqueous layer is filtered, and the isolated solid is washed (H2O) and dried to give 640 mg (68%) of 8 as a yellow solid, mp >260° C. (dec). IR 3328, 2945, 1608, 1221 cm−1; 1H NMR (DMSO-d6) δ 2.74(s, 3H, CH3), 7.30 (d, J=1.8 Hz, 1H, 5-PhthH), 7.53 (dd, J=8.5, 1.8 Hz, 1H, 7-PhthH), 8.08 ppm (d, J=8.5 Hz, 1H, 8-PhthH).

Provenance & Evidence