Hydrochloric Acid → 6,7-Dihydro-5H-pyrazolo[5,1-b][1,3]oxazine-2-carboxylic acid

Participants

Reaction Steps

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

Provenance & Evidence