Phosphorus oxychloride → 1,6-Dichlorophthalazine

Participants

Reaction Conditions

Reaction Steps

A mixture of 6-chlorophthalazin-1(2H)-one (10.0 g, 55.4 mmol) and phosphoryl trichloride (50.0 mL, 538 mmol) was heated at 105° C. in an oil bath for 8 h. After cooling to RT, the mixture was concentrated by vacuum distillation. The brown residue was re-dissolved in CH2Cl2 and neutralized with saturated aq. NaHCO3. After stirring for 3 h, the organic layer was collected and the aqueous layer was extracted with CH2Cl2 (3×). The combined organics were dried over Na2SO4, filtered through a pad of silica gel, eluting with EtOAc, and concentrated to give the title compound as a tan solid. MS (ESI, pos. ion) m/z: 199.0 (M+1).

Provenance & Evidence