Hydrochloric Acid → 8-Fluoro-3-phenyl-3a,4-dihydro-3H-pyrazolo(5,1-c)(1,4)benzoxazine-2-carboxylic acid

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Reaction Steps

A solution of the racemic ester (1-6) (0.5 g, 1.5 mmol) in EtOH (10 mL) was treated with 12N HCl (10 mL) and heated at reflux for 8 h. The reaction was cooled to room temperature and neutralized with 3N NaOH and the mixture extracted with EtOAc (50 mL). The organic solution was washed with brine, dried over MgSO4, filtered, and concentrated. The residue was dissolved in MeCN (0.5 mL) and purified by reverse phase HPLC (YMC J-sphere H80 20×50 mm; eluted with 5-95% MeCN/water+0.1% TFA) to provide racemic (3-1). 1H NMR (500 MHz, CDCl3) δ 7.33 (m, 6H), 7.02 (m, 1H), 6.85 (m, 1H), 4.33 (m, 2H), 4.22 (m, 1H), 3.64 (m, 1H) ppm.

Provenance & Evidence