Reaction #2254182

Reaction equation

Acetyl chloride

AlCl3

2-bromo-3-methylthiophene

→

1-(5-bromo-4-methyl-thiophen-2-yl)-ethanone

Yield 56.6%

Solvents

dichloromethane

Conditions

Workup

1. 1
   workup.WAITAfter 1 hour at 0° C.
2. 2
   Otherthe reaction is quenched
3. 3
   workup.ADDITIONby added water (100 ml)
4. 4
   ExtractionThe mixture is extracted three times with dichloromethane
5. 5
   Dryingdried over MgSO4
6. 6
   Concentrationconcentrated in vacuo
7. 7
   OtherThe crude product is purified by chromatography on silica gel (180 g)
8. 8
   Washeluting with a mixture of ethyl acetate and heptane (1:6)

Procedure

Acetyl chloride (7.09 g) is added to a suspension of AlCl3 (11.53 g) in dichloromethane (310 ml) at 0° C. After 45 minutes at 0° C., 2-bromo-3-methylthiophene (5.0 g) is added dropwise. After 1 hour at 0° C., the reaction is quenched by added water (100 ml). The mixture is extracted three times with dichloromethane. The organic phases are combined, dried over MgSO4 and concentrated in vacuo. The crude product is purified by chromatography on silica gel (180 g) eluting with a mixture of ethyl acetate and heptane (1:6) to yield 1-(5-bromo-4-methyl-thiophen-2-yl)-ethanone (3.5 g) as a brown solid.

Source