Potassium Carbonate → 2-(7-Bromo-3,3-dimethyl-2,3-dihydro-benzofuran-5-yl)-oxazole

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Reaction Steps

To a solution of 7-bromo-3,3-dimethyl-2,3-dihydrobenzofuran-5-carboxylic acid (example 3b) (1.8 g, 6.64 mmol) in dichloromethane (40 mL) was added several drops of DMF followed by a solution of thionyl chloride in dichloromethane (2.0M, 6.64 mL, 13.3 mmol) at 0° C. under argon. After the addition, the mixture was stirred at room temperature for 5 hours. The solvent and excess of thinoyl chloride were removed under reduced pressure. The residue was dissolved in tetramethylene sulfone (10 mL) and potassium carbonate (1.84 g, 13.3 mmol) and 1H-1,2,3-triazole (504 mg, 7.3 mmol) were added under argon and the mixture was heated to 140° C. for 16 hours. The solution was cooled to room temperature, water was added and the mixture was extracted with EtOAc, washed with brine, dried over MgSO4, filtered and evaporated under reduced pressure. The residue was purified by column chromatography on silica gel (hexane: EtOAc/5:1) to give 900 mg of 2-(7-Bromo-3,3-dimethyl-2,3-dihydro-benzofuran-5-yl)-oxazole (46%). 1H NMR (300 MHz, CDCl3, ppm): δ: 1.40 (s, 6H), 4.41 (s, 2H), 7.19 (s, 1H), 7.67 (s, 1H), 7.75 (d, J=0.88 Hz, 1H), 8.01 (d, J=0.88 Hz).

Provenance & Evidence