Trifluoroacetic acid → 3-(4-Bromo-benzyl)-2-butyl-benzofuran

Temperature

0 °C

A solution of (4-bromo-phenyl)-(2-butyl-benzofuran-3-yl)-methanone (2.25 g, 6.32 mmol) in ethanol (20 mL, 0.3 M) was cooled to 0° C. and treated with NaBH4 (0.263 g, 1.1 equiv, 6.95 mmol). After stirring for 1 h, the mixture was poured into a 50% ether in water solution (200 mL). After separation, the aqueous layer was extracted with ether (50 mL) and the combined organic layers were washed with water, sat'd aq NaCl, dried over anhydrous MgSO4, filtered and concentrated in vacuo. The resulting alcohol was subsequently dissolved in dry dichloromethane (50 mL), cooled to 0° C. and treated with triethylsilane (2.0 mL, 2.0 equiv., 12.64 mmol) dropwise via syringe. After stirring an additional 5 min, trifluoroacetic acid (2.43 mL, 5.0 equiv., 31.6 mmol) was added over 2 min and the mixture was stirred for 3 h. Once complete, the solution was washed with water, sat'd aq NaCl, dried over anhydrous MgSO4, filtered and concentrated in vacuo. Purification by flash column chromatography (0-2% ethyl acetate in heptane) afforded 3-(4-bromo-benzyl)-2-butyl-benzofuran as a pale yellow oil (1.34 g, 63%).

1. customAfter separation
2. extractionthe aqueous layer was extracted with ether (50 mL)
3. washthe combined organic layers were washed with water
4. dry with materialdried over anhydrous MgSO4
5. filtrationfiltered
6. concentrationconcentrated in vacuo
7. dissolutionThe resulting alcohol was subsequently dissolved in dry dichloromethane (50 mL)
8. stirringAfter stirring an additional 5 min
9. stirringthe mixture was stirred for 3 h
10. washOnce complete, the solution was washed with water
11. dry with materialdried over anhydrous MgSO4
12. filtrationfiltered
13. concentrationconcentrated in vacuo
14. customPurification by flash column chromatography (0-2% ethyl acetate in heptane)

ORD record

ord-4f1229f5ba7c45a689b7e0db745d70ab

Source dataset

uspto-grants-2008_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07329680B2