Hydrogen Peroxide → 1,3-Dibromo-5-(1,1-dimethylethoxy)benzene

Temperature

-78 °C

To a vigorously stirred solution of 1,3-dibromophenylboronic acid (4.5 g, 16.1 mmol) in MeOH (50 mL) and THF (50 mL) was alternately added (dropwise) aqueous hydrogen peroxide (30%, 10 mL) and NaOH (1M, 20 mL) (dropwise), maintaining pH˜10. The solution became cloudy and was stirred for 30 min (pH maintained at ˜10 using 10 N NaOH). EtOAc (200 mL) and sat'd NaHCO3 (50 mL) were added and the layers were separated. The organic layer was extracted with NaHCO3 (50 mL), water (20 mL), brine (50 mL), and was dried over sodium sulfate. The solvent was removed in vacuo and the residue was dissolved in DCM (80 mL). After cooling to −78° C., isobutylene was added (˜20 mL) followed by trifluoromethanesulfonic acid (300 μL). The cloudy solution was stirred for 15 min at −78° C. and for 1 h at −20 to −10° C. Additional amounts of isobutylene (˜10 mL) and trifluoromethanesulfonic acid (200 μL) were added and the solution was stirred for 1 h. Solid K2CO3 (1 g) was carefully added, the solution was stirred for 10 min at rt, and NaOH (1N, 30 mL) was added. The layers were separated and the organic layer was further extracted with NaOH (1N, 5×10 mL), water (10 mL), and brine (30 mL). After drying and removal of the solvent in vacuo, the residue was purified by SiO2 flash chromatography (2–5% EtOAc in hexanes) to yield the title compound (3.80 g, 77%). 1H-NMR (CDCl3): δ 7.38 (t, 1H, J=1.6 Hz), 7.09 (d, 2H, J=1.6 Hz), 1.36 (s, 9H).

1. temperaturemaintaining pH˜10
2. customthe layers were separated
3. extractionThe organic layer was extracted with NaHCO3 (50 mL), water (20 mL), brine (50 mL)
4. dry with materialwas dried over sodium sulfate
5. customThe solvent was removed in vacuo
6. dissolutionthe residue was dissolved in DCM (80 mL)
7. additionisobutylene was added (˜20 mL)
8. stirringThe cloudy solution was stirred for 15 min at −78° C. and for 1 h at −20 to −10° C
9. additionAdditional amounts of isobutylene (˜10 mL) and trifluoromethanesulfonic acid (200 μL) were added
10. stirringthe solution was stirred for 1 h
11. additionSolid K2CO3 (1 g) was carefully added
12. stirringthe solution was stirred for 10 min at rt
13. additionNaOH (1N, 30 mL) was added
14. customThe layers were separated
15. extractionthe organic layer was further extracted with NaOH (1N, 5×10 mL), water (10 mL), and brine (30 mL)
16. customAfter drying
17. customremoval of the solvent in vacuo
18. customthe residue was purified by SiO2 flash chromatography (2–5% EtOAc in hexanes)

ORD record

ord-a7b30be0547347f6a66506a2ac855733

Source dataset

uspto-grants-2006_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07138530B2