Реакция #1708913

Уравнение реакции

6-Fluoronicotinaldehyde

ethylene glycol

p-toluenesulfonic acid

→

5-(1,3-dioxolan-2-yl)-2-fluoropyridine

Выход 64.0%

Растворители

toluene

sodium bicarbonate

water

EtOAc

Условия реакции

Обработка

1. 1
   ДругоеThe flask was fitted with a Dean-Stark head and a reflux condenser
2. 2
   Другоеplaced in a preheated oil bath
3. 3
   Температураthe reaction was cooled to room temperature
4. 4
   ДругоеThe layers were separated
5. 5
   Экстракцияthe aqueous phase was extracted with EtOAc
6. 6
   Сушкаdried over sodium sulfate
7. 7
   Фильтрацияfiltered
8. 8
   Концентрированиеconcentrated
9. 9
   Другоеpurified on a silica gel
10. 10
    Фильтрацияfilter (600 mL fritted filter with about 3 inches of silica gel; DCM to 100:1 to 50:1 DCM/MeOH to 40:1 DCM/MeOH)

Методика

6-Fluoronicotinaldehyde (21.96 g, 176 mmol) was suspended in toluene (340 mL) and ethylene glycol (10.4 mL, 186 mmol) and p-toluenesulfonic acid (Acros, 15% in acetic acid, 1.10 mL) were added. The flask was fitted with a Dean-Stark head and a reflux condenser, and placed in a preheated oil bath (120° C.) and the reaction was stirred. After 45 minutes, the reaction was cooled to room temperature. The reaction was diluted with saturated sodium bicarbonate (50 mL), water (150 mL) and EtOAc (150 mL). The layers were separated and the aqueous phase was extracted with EtOAc. The organic phases were combined, dried over sodium sulfate, filtered, concentrated, and purified on a silica gel filter (600 mL fritted filter with about 3 inches of silica gel; DCM to 100:1 to 50:1 DCM/MeOH to 40:1 DCM/MeOH) to give 19.055 g of 5-(1,3-dioxolan-2-yl)-2-fluoropyridine. m/z (ESI, +ve ion) 170 (M+H)+.

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