反应详情

A solution of 1-acetyl-4-piperidone (17.0 g, 121 mmol), trimethyl orthoformate (26.4 mL, 241 mmol) and para-toluenesulfonic acid monohydrate (80 mg, 0.42 mmol) in dry methanol (34 mL) was refluxed for one hour. Then 1.0 M methanolic NaOMe (0.42 mL, 0.42 mmol) and excess of methanol and trimethyl orthoformate were removed by distillation (atmospheric pressure). Further distillation under reduced pressure afforded 1-acetyl-4,4-dimethoxy-piperidine (20.2 g, 89%) 1H NMR (DMSO) δ 3.45-3.32 (m, 4H), 3.10 (s, 6H), 1.99 (s, 3H), 1.72-1.62 (m, 2H), 1.61-1.52 (m, 2H).

1. distillationFurther distillation under reduced pressure