Boron trifluoride etherate → 3-Bromo-9H-xanthen-9-one

Participants

Reaction Steps

To a suspension of 4-bromo-2-phenoxy-benzoic acid (5 g, 17 mmol) in CH2Cl2 (50 mL) was added dropwise trifluoroacetic anhydride (2.9 mL, 20.53 mmol) at room temperature. The mixture was stirred at room temperature for 5 min. To this solution was added dropwise boron trifluoride diethyl etherate (0.215 mL, 1.7 mmol) at 0° C. After 30 min, the reaction was allowed to warm to room temperature. The mixture was stirred at room temperature for 2 h, at which time the mixture was poured into 1 N NaOH (35 mL) that was cooled to about 3° C. The aqueous layer was extracted with CH2Cl2 (2×10 mL). The combined organic layers were washed with brine, dried (MgSO4) and concentrated. Heptane was added to the residue and the resulting solid was collected by filtration to give Compound 1c. MS m/z (MH+) 276.7; 1H NMR (CDCl3,) δ 7.43 (t, 1H), 7.52 (m, 2H), 7.76 (m, 2H), 8.23 (d, 1H), 8.35 (dd, 1H).

Provenance & Evidence