反应详情

Following the procedure of Cohen (J. Am. Chem. Soc., 1964, 86, 5326), the resultant compound from Example 89 (8.6 g, 52 mmol) was dissolved in dry methanol (250 ml). p-Toluenesulfonic acid (2 g, 10.5 mmol) was added and the solution was refluxed for 2 h. The cooled solution was concentrated in vacuo and the residue was dissolved in ether (400 ml). The ether solution was washed with saturated aqueous NaHCO3 (3×50 ml), water (2×50 ml), 0.1N H2SO4 (1×50 ml), water (1×50 ml), dried over Na2SO4, and concentrated in vacuo to afford a colorless solid. The solid was recrystallized from hexane to provide the title compound as colorless needles (7.7 g, 83%); mp=46°-47° C.

1. temperaturethe solution was refluxed for 2 h
2. concentrationThe cooled solution was concentrated in vacuo
3. dissolutionthe residue was dissolved in ether (400 ml)
4. washThe ether solution was washed with saturated aqueous NaHCO3 (3×50 ml), water (2×50 ml), 0.1N H2SO4 (1×50 ml), water (1×50 ml)
5. dry with materialdried over Na2SO4
6. concentrationconcentrated in vacuo
7. customto afford a colorless solid
8. customThe solid was recrystallized from hexane