Reaction #2254178

Reaction equation

Ethylene glycol

p-toluenesulfonic acid

2-brom-3-methyl-5-formylthiophene

→

2-(5-bromo-4-methyl-thiophen-2-yl)-[1,3]dioxolane

Solvents

toluene

Conditions

Workup

1. 1
   TemperatureAfter 18 hours at reflux
2. 2
   Otherthe reaction is quenched with water
3. 3
   OtherThe organic phase is separated
4. 4
   Extractionthe aqueous phase is extracted three times with ethyl acetate
5. 5
   DryingThe combined organic phases are dried over Na2SO4
6. 6
   Concentrationconcentrated in vacuo
7. 7
   OtherThe crude product is purified on a semi-preparative HPLC

Procedure

Ethylene glycol (2.18 ml) and p-toluenesulfonic acid (0.74 g) is added to a solution of 2-brom-3-methyl-5-formylthiophene (4.0 g) in toluene (98 ml) in a Dean-Stark apparatus. After 18 hours at reflux, the reaction is quenched with water. The organic phase is separated and the aqueous phase is extracted three times with ethyl acetate. The combined organic phases are dried over Na2SO4 and concentrated in vacuo. The crude product is purified on a semi-preparative HPLC to yield 2-(5-bromo-4-methyl-thiophen-2-yl)-[1,3]dioxolane (4.04 g) as a yellow oil. MS (HPLC/MS): 250 (MH+). Retention time: 4.02 min.

Source