Ethyl 6-chloro-7-(4-(4-chlorophenethylcarbamoyl) phenoxy)chroman-4-carboxylate (128.8 g, 250.4 mmol) was dissolved in EtOH (250 mL) and THF (500 mL). NaOH (6N) (62.60 ml, 375.6 mmol) was added and the mixture was stirred at ambient temperature for 1.5 hours. The mixture was transferred to a 2 L separatory funnel and 1N HCl (500.8 ml, 500.8 mmol) was added to the mixture. Additional EtOAc (250 ml) was added and the layers were separated. The organic layer was washed with water and brine, dried over magnesium sulfate, filtered, and concentrated under reduced pressure. The resulting crude solid was recrystallized from THF and hexanes to provide 122.0 g of the title compound as a faint pink solid (yield 95.0%). 1H NMR analysis showed that the solid contained THF. The THF content was 27 mol % (5.2% weight) and the desired product content by weight was 94.8%. MS (apci) m/z=486.1 (M+H).
