Reaktion #2414

Reaktionsgleichung

thiophene

n-butyl lithium n-hexane

2,3-dichloro-5,6-dicyano-1,4-benzoquinone

charcoal

5-(4-methylphenyl)-4,6-dichloropyrimidine

→

5-(4-methylphenyl)-4,6-dichloro-2-(2-thienyl)pyrimidine

Ausbeute 49.1%

Lösungsmittel

water

acetic acid

tetrahydrofuran

tetrahydrofuran

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONTo the mixture is added dropwise
2. 2
   Sonstigeat -60° C
3. 3
   workup.ADDITIONfurther added
4. 4
   Extraktionextracted with a mixture of ethyl acetate and aqueous citric acid solution
5. 5
   WaschenThe extract is washed
6. 6
   Sonstigedried
7. 7
   Sonstigeevaporated
8. 8
   Sonstigeto remove the solvent
9. 9
   SonstigeThe residue is purified by silica gel column chromatography (solvent; n-hexane/ethyl acetate=50:1)

Vorschrift

To a solution of thiophene (1.69 g) in anhydrous tetrahydrofuran (20 ml) is added dropwise a 1.6M n-butyl lithium/n-hexane solution (11.4 ml) at 0° C. under argon atmosphere over a period of 30 minutes. To the mixture is added dropwise and gradually a solution of 5-(4-methylphenyl)-4,6-dichloropyrimidine (4.0 g) in anhydrous tetrahydrofuran (5 ml) at -60° C. The mixture is warmed to 0° C., and stirred for 1.5 hour. After the reaction is complete, to the mixture are added acetic acid (1.5 g) and water (0.25 g), and further added thereto a solution of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (5.70 g) in tetrahydrofuran (5 ml), and the mixture is stirred at 0° C. for one hour. The mixture is treated with an active charcoal, and extracted with a mixture of ethyl acetate and aqueous citric acid solution. The extract is washed, dried and evaporated to remove the solvent. The residue is purified by silica gel column chromatography (solvent; n-hexane/ethyl acetate=50:1) to give 5-(4-methylphenyl)-4,6-dichloro-2-(2-thienyl)pyrimidine (2.64 g) as powder.

Quelle