[F:1][C:2]1[CH:7]=[CH:6][C:5]([C:8](=[O:18])[CH2:9][C:10]2[CH:15]=[CH:14][N:13]=[C:12]([S:16][CH3:17])[N:11]=2)=[CH:4][CH:3]=1.[N:19](OC(C)(C)C)=[O:20].Cl>C(O)C.C(O)CC>[F:1][C:2]1[CH:7]=[CH:6][C:5]([C:8](=[O:18])/[C:9](=[N:19]\[OH:20])/[C:10]2[CH:15]=[CH:14][N:13]=[C:12]([S:16][CH3:17])[N:11]=2)=[CH:4][CH:3]=1To a suspension of 1-(4-fluorophenyl)-2-(2-(methylthio)pyrimidin-4-yl)ethanone, 73 (1.0 g) in ethanol (20 mL) at −10° C., under an atmosphere of nitrogen, is added dropwise t-butyl nitrite (0.5 mL) followed by hydrogen chloride in n-propanol (2.5 to 3 N, 0.6 mL) while maintaining the temperature below −5° C. Once the addition is complete, the solution is allowed to warm to room temperature with stirring and after 2 h the solvent is evaporated and the residue partitioned between saturated aqueous sodium hydrogen carbonate and ethyl acetate. The layers are separated; the aqueous phase is extracted with ethyl acetate and the combined organic phases dried over sodium sulfate. Filtration and evaporation of the solvent affords the title compound, 74 (1.0 g).
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