Cl[C:2]1[N:7]2[N:8]=[CH:9][C:10]([C:11]([O:13]CC)=[O:12])=[C:6]2[N:5]=[CH:4][CH:3]=1.[CH3:16][NH:17][CH2:18][CH3:19].[OH-].[Na+].Cl>CC#N.CCO.O>[CH2:18]([N:17]([CH3:16])[C:2]1[N:7]2[N:8]=[CH:9][C:10]([C:11]([OH:13])=[O:12])=[C:6]2[N:5]=[CH:4][CH:3]=1)[CH3:19]To a solution of ethyl 7-chloropyrazolo[1,5-a]pyrimidine-3-carboxylate (68 mg, 0.30 mmol) in CH3CN (1 mL) was added N-methylethanamine (18 mg, 0.30 mmol) and the mixture was stirred at ambient temperature for 16 h. The mixture was evaporated and the residue was purified by column chromatography (0-10% MeOH in dichloromethane) to give a solid. The solid was taken up in EtOH (0.5 mL) and water (0.1 mL) before NaOH (12 mg, 0.30 mmol) was added. The mixture was stirred at 50° C. for 4 h. The pH of the mixture was adjusted to 4 with conc. HCl, and the solvents were removed. The residue was co-evaporated with MeOH (3×) to provide 7-(ethyl(methyl)amino)pyrazolo[1,5-a]pyrimidine-3-carboxylic acid. ESI-MS m/z calc. 220.1, found 221.5 (M+1)+; Retention time: 0.29 minutes (3 min run).
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