反应详情

A mixture of tetrahydro-(4H)-thiopyran-4-one (15.0 g, 129 mmol), trimethyl orthoformate (28.3 mL, 258 mmol) and para-toluenesulfonic acid monohydrate (67 mg, 0.35 mmol) in methanol (40 mL) was refluxed for 1 hour. The reaction mixture was cooled to room temperature, 1 M NaOMe (0.35 mL, 0.35 mmol) was added and excess methanol and trimethyl orthoformate was removed by distillation (atmospheric pressure). Further distillation under reduced pressure afforded 4,4-dimethoxytetrahydro-(4H)-thiopyran (20.7 g, 99%). 1H NMR (DMSO) δ 3.07 (s, 6H), 2.56 (m, 4H), 1.84 (m, 4H).

1. temperaturewas refluxed for 1 hour
2. customexcess methanol and trimethyl orthoformate was removed by distillation (atmospheric pressure)
3. distillationFurther distillation under reduced pressure