Trifluoroacetic acid → 5-Bromo-7-isopropyl-3,3,6-trimethyl-2,3-dihydro-benzofuran

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Reaction Steps

A stirred, cooled (ice bath)solution of 2-(5-bromo-3,3,6-trimethyl-2,3-dihydro-benzofuran-7-yl)-propan-2-ol (Compound 49, 1.51 g, 5.03 mmol) in 15 mL of dichloromethane was treated with triethyl silane (1.4 mL, 8.76 mmol) followed by trifluoroacetic acid (0.65 mL, 8.43 mmol) and the resulting clear, colorless solution was stirred at ambient temperature overnight. The reaction mixture was cooled, treated with 6 mL each of methanol and water, neutralized cautiously with saturated sodium bicarbonate solution and extracted with diethylether. The organic extract was dried over anhydrous sodium sulfate, filtered and evaporated to an oil. Flash column chromatography using 0.5% ethyl acetate in hexanes as the eluent afforded the title compound (1.36 g, 95%) as an oil. 1H NMR (300 MHz, CDCl3): δ 7.11 (s, 1H), 4.18 (s, 2H), 3.25 (heptet, 1H, J=7.1 Hz), 2.40 (s, 3H), 1.30 (s, 6H), 1.31 (d, 6H, J=7.1 Hz).

Provenance & Evidence