反应详情

N-Bromosuccinimide (2.6 g, 0.016 mol) in dimethylformamide (40 ml) was added dropwise to a stirred solution of 5-(2-n-propoxyphenyl)-1-methyl-3-n-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]-pyrimidin-7-one (Preparation 10, 4.0 g. 0.010 mol) in dimethylformamide (40 ml) at room temperature. After 7 hours the solvent was removed by evaporation under vacuum, the residue suspended in saturated aqueous sodium carbonate solution, and the resulting solution extracted with ethyl acetate (3×50 ml). The organic extracts were combined, dried (Na2SO4) and evaporated under vacuum. Trituration of the residue with ether, followed by crystallisation from ethyl acetate-hexane, gave the title compound as white crystals (3.39 g, 68%), m.p. 117°-118° C. Found C,53.15; H, 5.03; N,13.78. C18H21BrN4O2 requires C,53.34; H,5.22; N,13.82%.

1. customAfter 7 hours the solvent was removed by evaporation under vacuum
2. extractionthe resulting solution extracted with ethyl acetate (3×50 ml)
3. dry with materialdried (Na2SO4)
4. customevaporated under vacuum
5. customTrituration of the residue with ether, followed by crystallisation from ethyl acetate-hexane