Bromine → 5-(5-Bromo-2-ethoxyphenyl)-1-methyl-3-propyl-1H-pyrazolo[4,3-D]pyrimidin-7(6H)-one

Participants

Reaction Conditions

Reaction Steps

Bromine (0.93 g, 0.0058 mol) was added dropwise to a stirred solution of 5-(2-ethoxyphenyl)-1-methyl-3-n-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one (Preparation 7, 1.1 g, 0.00352 mol) in glacial acetic acid (20 ml). The mixture was stirred at 100° C. for 6.5 hours and the solvent was then removed by evaporation under vacuum. The residue was dissolved in a 9:1 mixture of methanol in dichloromethane (50 ml), and the solution washed with saturated aqueous sodium bicarbonate solution (50 ml), water (50 ml) and saturated brine (50 ml), then dried (MgSO4) and evaporated under vacuum. The residue was chromatographed on silica gel (15 g) eluting with a mixture of methanol and dichloromethane (1:99) to give, after crystallisation from acetonitrile, the title compound (0.62 g, 45%), m.p. 157°-159° C. Found: C,52.41; H,5.25; N,14.01. C17H19BrN4O2 requires C, 52.18; H,4.89; N,14.32%.

Provenance & Evidence