[Br:1][C:2]1[C:10]2[C:9](N)=[N:8][CH:7]=[N:6][C:5]=2[O:4][C:3]=1[C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1.[ClH:18].O1CCOCC1.N(OCCC(C)C)=O>C(Cl)(Cl)Cl.O>[Br:1][C:2]1[C:10]2[C:9]([Cl:18])=[N:8][CH:7]=[N:6][C:5]=2[O:4][C:3]=1[C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1
Put 54 g (186 mmol) 5-bromo-6-phenylfuro[2,3-d]pyrimidine-4-amine in 135 ml chloroform, add 70 ml 4 N hydrogen chloride in dioxan (280 mmol) and heat to reflux. Add 50 ml (372 mmol) isoamyl nitrite dropwise (evolution of gas). At the end of addition, stir for 3 h under reflux, before adding the cooled reaction mixture to water and extracting it with dichloromethane. Wash the organic phase with satd. sodium hydrogencarbonate solution, dry over sodium sulphate and concentrate by vacuum evaporation. Purify the raw product by chromatography on silica gel (eluent: dichloromethane). For further purification, mix the product in methanol, filter with suction, and dry at high vacuum. 32 g of the target product (55.5% of theor.) is obtained.
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