O[C:2]1[N:7]2[N:8]=[CH:9][C:10]([C:11]([O:13][CH2:14][CH3:15])=[O:12])=[C:6]2[N:5]=[CH:4][CH:3]=1.O=P(Cl)(Cl)[Cl:18].[OH-].[Na+].C([O-])([O-])=O.[Na+].[Na+]>CN(C)C1C=CC=CC=1>[Cl:18][C:2]1[N:7]2[N:8]=[CH:9][C:10]([C:11]([O:13][CH2:14][CH3:15])=[O:12])=[C:6]2[N:5]=[CH:4][CH:3]=1
To a stirred suspension ethyl 7-hydroxypyrazolo[1,5-a]pyrimidine-3-carboxylate (0.95 g, 4.6 mmol) in POCl3 (8.0 mL, 86 mmol) was added dimethyl aniline (0.8 μL, 0.006 mmol) and the mixture was heated at 80° C. for 2 hours. The mixture was slowly poured onto ice, and the pH was carefully adjusted to ˜7 with 1N NaOH, then to pH 10 with solid Na2CO3. The mixture was then extracted with dichloromethane (3×). The organics were combined, washed with brine, dried (MgSO4) and evaporated to dryness. Trituration of the solids with hexanes gave ethyl 7-chloropyrazolo[1,5-a]pyrimidine-3-carboxylate (260 mg, 25%) as a tan solid. ESI-MS m/z calc. 225.0, found 226.5 (M+1)+; Retention time: 0.87 minutes (3 min run).
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