Reaction #2507835

Reaction equation

Ethyleneglycol

p-toluenesulfonic acid

5-bromopyridine-2-carbaldehyde

→

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

Yield 84.0%

Solvents

toluene

Conditions

Workup

1. 1
   Temperatureat refluxing temperature
2. 2
   Otherthe mixture is quenched with saturated aqueous NH4Cl
3. 3
   Extractionextracted with CH2Cl2
4. 4
   Washwashed with H2O
5. 5
   ExtractionThe aqueous layer is extracted with CH2Cl2
6. 6
   Extractionthe combined organic extract
7. 7
   Washis washed with brine
8. 8
   Dryingdried over Na2SO4
9. 9
   Concentrationconcentrated under reduced pressure
10. 10
    OtherThe residue is purified by silica gel column chromatography (hexane-AcOEt (9:1 V/V))

Procedure

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).

Source