Phosphorus oxychloride → 3-chloro-1-(4-trifluoromethoxyphenyl)-4,5-dihydro-1H-pyrazole

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Reaction Conditions

Reaction Steps

The general procedure was taken from Wang et al. Tetrahedron Lett. 2005, 46, 2631. To a solution of 1-(4-trifluoromethoxyphenyl)-pyrazolidin-3-one (120 mg, 0.49 mmol, 1.00 eq) in toluene (20 mL) was slowly added phosphoryl chloride (22.5 mg, 1.47 mmol, 3.00 eq). The mixture was then heated at 80° C. for 1 h before cooling to room temperature and quenching with H2O (10 mL). The vessel was stirred under an atmosphere of nitrogen (N2) for 8 h before the product was extracted into EtOAc (200 mL), dried (MgSO4), and concentrated under reduced pressure. GC-MS proved 88% formation of the desired intermediate, which was used in subsequent reactions without further purification.

Provenance & Evidence