Reaction #76091

Reaction equation

3-[4-(2-heptylamino-ethyl)-phenyl]-2,2-dimethyl-propionic acid ethyl ester

boron tribromide

H2O

boron tribromide

→

3-[4-(2-heptylamino-ethyl)-phenyl]-2,2-dimethyl-propionic acid

Solvents

methylene chloride

dichloromethane

Conditions

Workup

1. 1
   TemperatureThe mixture was warmed to room temperature
2. 2
   TemperatureThe mixture was cooled to −78° C.
3. 3
   TemperatureThe mixture was warmed to room temperature
4. 4
   workup.STIRRINGstirred for 20 minutes
5. 5
   Extractionextracted with dichloromethane (3×)
6. 6
   Dryingdried over anhydrous sodium sulfate
7. 7
   Concentrationconcentrated to a clear film
8. 8
   workup.DISSOLUTIONThis was dissolved in dioxane/2M HCl (10 mL/10 mL)
9. 9
   Temperaturewas refluxed for 20 minutes
10. 10
    TemperatureThe mixture was cooled
11. 11
    WashThe basic solution was washed with diethyl ether (3×)
12. 12
    ExtractionThe acidic solution was extracted with diethyl ether (3×)
13. 13
    Washwashed with brine (2×)
14. 14
    Dryingdried over anhydrous sodium sulfate
15. 15
    Concentrationconcentrated

Procedure

To a solution of the impure 3-[4-(2-heptylamino-ethyl)-phenyl]-2,2-dimethyl-propionic acid ethyl ester (100 mg of the mixture) dissolved in methylene chloride (5 mL) cooled to −78° C. under a nitrogen atmosphere was added boron tribromide (1M in dichloromethane, 0.432 mL). The mixture was warmed to room temperature and stirred for 3 h. The mixture was cooled to −78° C. and an additional 0.432 mL of the 1M boron tribromide in dichloromethane was added. The mixture was warmed to room temperature and stirred for 20 minutes. The mixture was poured over H2O (10 mL) and extracted with dichloromethane (3×). The organic layers were combined, dried over anhydrous sodium sulfate, and concentrated to a clear film. This was dissolved in dioxane/2M HCl (10 mL/10 mL) and was refluxed for 20 minutes. The mixture was cooled and brought to pH 10 with 2 N NaOH. The basic solution was washed with diethyl ether (3×) and brought to pH 4 with 2N HCL. The acidic solution was extracted with diethyl ether (3×), washed with brine (2×), dried over anhydrous sodium sulfate and concentrated to give 3-[4-(2-heptylamino-ethyl)-phenyl]-2,2-dimethyl-propionic acid as a clear film (23 mg, 46%).

Source