Reaktion #2507835

Reaktionsgleichung

Ethyleneglycol

p-toluenesulfonic acid

5-bromopyridine-2-carbaldehyde

→

5-bromo-2-(1,3-dioxolan-2-yl)pyridine

Ausbeute 84.0%

Lösungsmittel

toluene

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturat refluxing temperature
2. 2
   Sonstigethe mixture is quenched with saturated aqueous NH4Cl
3. 3
   Extraktionextracted with CH2Cl2
4. 4
   Waschenwashed with H2O
5. 5
   ExtraktionThe aqueous layer is extracted with CH2Cl2
6. 6
   Extraktionthe combined organic extract
7. 7
   Waschenis washed with brine
8. 8
   Trocknendried over Na2SO4
9. 9
   Einengenconcentrated under reduced pressure
10. 10
    SonstigeThe residue is purified by silica gel column chromatography (hexane-AcOEt (9:1 V/V))

Vorschrift

Ethyleneglycol (14.88 g, 0.24 mol) and p-toluenesulfonic acid (3 g, 0.16 mol) are added to a solution of 5-bromopyridine-2-carbaldehyde (30 g, 0.16 mol) in toluene (150 ml) at room temperature and the mixture is stirred for 10 hrs at refluxing temperature. After cooling to room temperature, the mixture is quenched with saturated aqueous NH4Cl, extracted with CH2Cl2 and washed with H2O. The aqueous layer is extracted with CH2Cl2 and the combined organic extract is washed with brine, dried over Na2SO4, and concentrated under reduced pressure. The residue is purified by silica gel column chromatography (hexane-AcOEt (9:1 V/V)) to afford 5-bromo-2-(1,3-dioxolan-2-yl)pyridine (30.9 g, 84%) as a colorless oil. %). 1H NMR (400 MHz, CDCl3) δ 8.69 (s, 1H), 7.87 (m, 1H), 7.45 (m, 1H), 5.83 (s, 1H), 4.13 (m, 4H).

Quelle