The crude product was extracted with DCM and the organic phase was separated. The aqueous phase was further extracted with DCM (4 x 50 mL). The combined organic phase was washed with water (3 x 50 mL) and brine (3 x 50 mL) then dried over Na2SO4, filtered, and evaporated under reduced pressure. Chromatography on silica gel with DCM 100% afforded the title compound 5c as an orange solid (1.46