反应详情

温度

50 °C

Neat chlorosulfonic acid (2 mL) was added to 2-(2-cyclopentylethyl)-5-phenyloxazole from Step B (500 mg, 2.07 mmol) at room temperature under nitrogen with stirring. To this brown solution was added sodium chloride (100 mg) in portions and then the mixture was heated at 50° C. in an oil bath. After 2 h at 50° C., the mixture was poured onto ice-water and extracted with ethyl acetate (3×10 mL). The combined organics were washed with saturated aqueous sodium bicarbonate solution, water, and brine, dried over sodium sulfate, and evaparated. The brown residue was chromatogaphed on silica gel (eluent: 2:3 ethyl acetate:hexanes) to give 500 mg (76.9%) of the title compound as an off-white solid: 1H NMR (400 MHz, CDCl3) δ 8.05 (d, 2H, J=8.2 Hz), 7.81 (d, 2H, J=8.2 Hz), 7.45 (s, 1H), 2.85 (t, 2H, 7.5 Hz), 1.90-1.75 (m, 5H), 1.70-1.48 (m, H), 1.12 (m, 2H).

1. additionthe mixture was poured onto ice-water
2. extractionextracted with ethyl acetate (3×10 mL)
3. washThe combined organics were washed with saturated aqueous sodium bicarbonate solution, water, and brine
4. dry with materialdried over sodium sulfate