反应详情

温度

60 °C

To a solution of Example 175A in anhydrous N,N-dimethyl formamide (10 mL) was added 2,2-dimethoxypropane (0.62 mL, 5.0 mmol) and p-toluenesulfonic acid monohydrate (50 mg, 0.26 mmol). The resulting mixture was stirred under a N2 atmosphere at 60° C. for 16 h. Additional 2,2-dimethoxypropane (0.3 mL, 2.4 mmol) and p-toluenesulfonic acid monohydrate (50 mg, 0.26 mmol) were added, and the mixture was stirred at 60° C. for 6 h. The mixture was partitioned between saturated NaHCO3 (50 mL) and ethyl acetate (3×50 mL), and the combined organic layers were dried over Na2SO4. The crude product was purified by column chromatography on silica gel using a solvent gradient of 50-65% ethyl acetate in hexane. The title compound was obtained as a colorless, crystalline solid (0.44 g, 62% for two steps). 1H NMR (300 MHz, CDCl3) δ 1.83 (s, 3 H), 1.88 (s, 3 H), 3.13 (m, 1 H), 3.40 (m, 1 H), 3.92 (m, 2 H), 3.98 (s, 3 H), 7.28 (m, 1 H), 7.37 (m, 1 H), 7.49 (m, 1 H), 7.71 (m, 1 H), 7.80 (m, 1 H), 7.86 (m, 1 H).

1. stirringthe mixture was stirred at 60° C. for 6 h
2. customThe mixture was partitioned between saturated NaHCO3 (50 mL) and ethyl acetate (3×50 mL)
3. dry with materialthe combined organic layers were dried over Na2SO4
4. customThe crude product was purified by column chromatography on silica gel using a solvent gradient of 50-65% ethyl acetate in hexane