Phosphorus tribromide → HCID 59603166, compound

Temperature

0 °C

A stirred solution of 20 (350 mg, 1.30 mmol) in acetic acid (10 mL) was refluxed for 24 h. After cooling, the solution was evaporated to dryness. The crude product (300 mg) was dissolved in THF (5 mL). NaBH4 (78 mg, 2.02 mmol) was added portionwise at 0° C., with vigorous stirring. The suspension was stirred at 0° C. for 15 min and then at room temperature for 1.5 h. Solvents were evaporated off in-vacuo. The crude residue (260 mg) was dissolved in toluene (20 mL) and the solution was cooled to 0° C. PBr3 (135 μL, 1.44 mmol) was added dropwise over 15 min. The reaction mixture was then brought up to room temperature and stirred for 1 h. The solvent was evaporated off in-vacuo. The residue was adsorbed on silica gel and purified by flash chromatography, eluting with hexane/EtOAc (4:1) to give 21 (200 mg, 36%). 1H NMR (500 MHz, CDCl3): δ: 7.03 (1H, d, J=7.50 Hz, H-4), 6.88 (1H, t, J=9.80, H-5), 6.75 (1H, s, H-3), 4.69 (2H, s, 2-CH2), 2.54 (3H, s, CH3).

1. temperatureAfter cooling
2. customthe solution was evaporated to dryness
3. dissolutionThe crude product (300 mg) was dissolved in THF (5 mL)
4. waitat room temperature for 1.5 h
5. customSolvents were evaporated off in-vacuo
6. dissolutionThe crude residue (260 mg) was dissolved in toluene (20 mL)
7. temperaturethe solution was cooled to 0° C
8. customwas then brought up to room temperature
9. stirringstirred for 1 h
10. customThe solvent was evaporated off in-vacuo
11. custompurified by flash chromatography
12. washeluting with hexane/EtOAc (4:1)

ORD record

ord-954261d0124b493f836a9f9597d4afde

Source dataset

uspto-grants-2012_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08283340B2