反应详情

To a solution of Example 123A (10.1 g, 50.5 mmol), trimethylorthoformate (20 mL), p-toluenesulfonic acid monohydrate (60 mg, 0.315 mmol) in methanol (100 mL) was heated at 60 C for 2 hours. After cooling to room temperature, the solution was concentrated in vacuo, and the resultant residue was purified by column chromatography employing 70-230 mesh silica gel eluting with hexane to provide the title compound as a colorless oil (7.8 g, 73%). 1H NMR (300 MHz, DMSO-d6): δ 1.38 (s, 3H), 2.44 (dd, J=13.8, 7.4 Hz, 1H), 2.65 (dd, J=13.6, 7.0 Hz, 1H), 3.41 (d, J=3.7 Hz, 2H), 3.54 (s, 3H), 4.75 (m, 2H), 4.90 (t, J=3.7 Hz, 1H), 5.24 (m, 1H), 7.10 (m, 2H), 7.19 (m, 1H), 7.40 (d, J=7.8 Hz, 1H).

1. concentrationthe solution was concentrated in vacuo
2. customthe resultant residue was purified by column chromatography