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

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).

1. waitAfter 30 min
2. temperatureto warm to room temperature
3. stirringThe mixture was stirred at room temperature for 2 h, at which time the mixture
4. temperaturewas cooled to about 3° C
5. extractionThe aqueous layer was extracted with CH2Cl2 (2×10 mL)
6. washThe combined organic layers were washed with brine
7. dry with materialdried (MgSO4)
8. concentrationconcentrated
9. additionHeptane was added to the residue
10. filtrationthe resulting solid was collected by filtration

ORD record

ord-a3a1516432cb4a3aba3540305365ab67

Source dataset

uspto-grants-2009_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07553850B2