Reaction #2271

Reaction equation

potassium carbonate

Phosphorus oxychloride

DMF

4-chlorophenylacetic acid

→

2-(4-chlorophenyl)-3-dimethylaminopropenal

Solvents

Toluene

Conditions

Workup

1. 1
   Temperatureheated to 70°-80° C. during 5.5 hours, during which time the mixture
2. 2
   TemperatureThe reaction mixture was cooled
3. 3
   workup.ADDITIONpoured slowly
4. 4
   workup.ADDITIONIce was added intermittently during this addition
5. 5
   Temperatureto maintain the temperature below 15° C
6. 6
   Temperaturethe resulting mixture heated at 100° C. for one hour
7. 7
   TemperatureThe mixture was cooled
8. 8
   OtherThe two resulting layers were separated
9. 9
   Extractionthe aqueous layer extracted with toluene (2×100 ml)
10. 10
    WashThe combined organic layers were washed with water (5×200 ml)
11. 11
    Dryingdried over anhydrous sodium sulfate
12. 12
    OtherThe solvent was evaporated in vacuo
13. 13
    Otherthe resulting yellow solid was triturated with hexane

Procedure

Phosphorus oxychloride (92 g) was added dropwise to stirred DMF (78 ml) between 10°-15° C. To the resulting slurry was added 4-chlorophenylacetic acid (34.12 g). The resulting mixture was stirred at room temperature for one half hour and then heated to 70°-80° C. during 5.5 hours, during which time the mixture became effervescent. The reaction mixture was cooled and poured slowly onto cracked ice. The resulting suspension was brought to pH 10 with solid potassium carbonate. Ice was added intermittently during this addition to maintain the temperature below 15° C. Toluene (150 ml) was added and the resulting mixture heated at 100° C. for one hour. The mixture was cooled and allowed to stand overnight. The two resulting layers were separated and the aqueous layer extracted with toluene (2×100 ml). The combined organic layers were washed with water (5×200 ml) and dried over anhydrous sodium sulfate. The solvent was evaporated in vacuo and the resulting yellow solid was triturated with hexane to yield 26 g of 2-(4-chlorophenyl)-3-dimethylaminopropenal as a tan solid mp. 120°-125° C.

Source