[OH:1][C:2]1[NH:6][N:5]=[C:4]([C:7]([O:9]CC)=[O:8])[CH:3]=1.Br[CH2:13][CH2:14][CH2:15]Br.C(=O)([O-])[O-].[K+].[K+].[OH-].[Na+].Cl>C(#N)C.CO.O>[N:5]1[N:6]2[C:2]([O:1][CH2:13][CH2:14][CH2:15]2)=[CH:3][C:4]=1[C:7]([OH:9])=[O:8]
Ethyl 5-hydroxy-1H-pyrazole-3-carboxylate (0.5 g, 3.20 mmol), 1,3-dibromopropane (0.358 mL, 3.52 mmol) and potassium carbonate (1.770 g, 12.81 mmol) were heated at reflux in acetonitrile (20 mL) for 20 h then cooled to RT, filtered and evaporated in vacuo. The residue was dissolved in a mixture of MeOH (10 mL) and water (20 mL), NaOH (0.384 g, 9.61 mmol) added and stirred for 2 h. The reaction mixture was adjusted to pH5 with 2M HCl and purified by reverse phase HPLC with MeCN/aqTFA as eluent. The solvent was evaporated in vacuo to ˜15 mL and freeze dried to give the sub-title compound as a white solid. Yield: 440 mg
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