Boron tribromide → 1-[2-(6-Hydroxy-2-naphthyl)-1-benzofuran-3-yl]-1-pentanone

Participants

Reaction Steps

To a cooled (−78° C.) solution of 1-[2-(6-methoxy-2-naphthyl)-1-benzofuran-3-yl]-1-pentanone (4.2 g, 12 mmol) in methylene chloride (45 mL), was added, dropwise, 1 N boron tribromide in methylene chloride (25 mL, 25 mmol). The reaction mixture was stirred at room temperature for 3 hours, 45 minutes. The mixture was cooled to −11° C. and quenched, dropwise, with methanol (25 mL), then poured into excess water, and diluted with additional methylene chloride. The organic phase was washed with brine, dried over anhydrous magnesium sulfate, filtered, and solvent evaporated. The residue was purified by flash chromatography (Biotage apparatus) using 5-20% ethyl acetate in hexane as an eluant to afford 1-[2-(6-hydroxy-2-naphthyl)-1-benzofuran-3-yl]-1-pentanone as a yellow solid (3.09 g), mp 148-149° C. Mass spectrum (+EI, M+) m/z 344; 1HNMR (400 MHz, DMSO-d6): δ10.1 (d, 1H, J=4.0 Hz), 8.3 (d, 1H, J=1.1 Hz), 8.0-8.05 (m, 1H), 7.95 (d, 1H, J=8.8 Hz), 7.85 (d, 1H, J=8.6 Hz), 7.7-7.75 (m, 2H), 7.35-7.45 (m, 2H), 7.15-7.25 (m, 2H), 2.75 (t, 2H, J=7.4 Hz), 1.5-1.55 (m, 2H), 1.1-1.15 (m, 2H), and 0.7 ppm (t, 3H, J=7.4 Hz). Elemental Analysis for C23H20O3: Calculated: C, 80.21; H, 5.85; N, 0.00. Found: C, 79.92; H, 5.81; N, 0.12.

Provenance & Evidence