Sulfuric Acid → 7-Hydroxy-2-Isopropyl-4-bromo-2H-phthalazin-1-one

Participants

Reaction Conditions

Reaction Steps

Concentrated sulfuric acid (17 ml) was added slowly to a solution of 7-amino-2-isopropyl-4-bromo-2H-phthalazin-1-one (4.6 g, 0.016 mol) in HOAc (50 ml). The reaction mixture was cooled to 0° C. and a solution of sodium nitrite (1.52 g, 0.022 mol) in water (10 ml) was added dropwise. The reaction mixture was stirred for a further 20 min at 0° C. prior to the addition of urea (0.55 g, 0.009 mol) and cold water (50 ml). The reaction mixture was then added carefully to a refluxing mixture of sulfuric acid (28 ml) in water (115 ml) and the reaction was stirred for a further 10 min at reflux before being allowed to cool to RT. Upon standing, an orange precipitate was observed, which was collected by filtration and washed with water to give the title compound (4.22 g, 93% yield) as an orange powder. δH (400 MHz, DMSO), 11.18 (1H, br s), 7.93 (1H, d), 7.71 (1 H, d), 7.53 (1H, dd), 5.34-5.26 (1H, m), 1.42 (6H, d)

Provenance & Evidence