A mixture of 7.5 (200 mg, 0.51 mmol), 1,3-dibromopropane (1.00 mL, 10 mmol), potassium carbonate (210 mg, 1.500 mmol) and tetrabutylammonium bromide (16 mg, 0.051 mmol) in water (6.0 mL) was heated to reflux and stirred for two hours. The mixture was then cooled to room temperature and extracted with EtOAc (2×50 mL). The combined organic layers were washed with brine and dried over magnesium sulfate. The filtrate was concentrated under reduced pressure and the residue was recrystallized with EtOAc and hexanes to obtain 48.1 (160 mg). MS ESI (pos.): m/e 514.0 (M+H).
