Reaktion #214437

Reaktionsgleichung

diisopropylamine

n-butyllithium

N-carbobenzyloxy-4-piperidone

Isobutyric acid

→

2-(1-carbobenzyloxy-4-hydroxypiperidin-4-yl)-2-methylpropionic acid

Ausbeute 51.4%

Lösungsmittel

diethyl ether

tetrahydrofuran

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturTo a 100 ml flask maintained under argon
2. 2
   TemperaturThe contents of the flask are cooled to 0°
3. 3
   Temperaturare maintained at that temperature
4. 4
   workup.STIRRINGthe mixture is stirred for 15 minutes at 20°
5. 5
   TemperaturThe mixture is cooled to -70°
6. 6
   Sonstigeremains below -50°
7. 7
   ExtraktionThis solution is extracted with two 150 ml portions of 1 N hydrochloric acid, 50 ml of water and 100 ml of 2% sodium hydroxide
8. 8
   Extraktionthe resulting mixture is extracted with three 50 ml portions of diethyl ether
9. 9
   SonstigeEvaporation of the ether
10. 10
    Sonstigeaffords an oil which
11. 11
    Sonstigeis triturated with 50 ml hexane

Vorschrift

To a 100 ml flask maintained under argon are added 2.22 g diisopropylamine and 15 ml tetrahydrofuran. The contents of the flask are cooled to 0° and are maintained at that temperature. A solution of 1.5 M n-butyllithium (14.7 ml) is added and the solution is stirred for five minutes. Isobutyric acid (0.88 g) is added and the mixture is stirred for 15 minutes at 20°. The mixture is cooled to -70° and a solution of 2.33 g of N-carbobenzyloxy-4-piperidone in 5 ml tetrahydrofuran is added at such a rate that the temperature remains below -50°. The mixture is allowed to warm to room temperature and is poured into 150 ml diethyl ether. This solution is extracted with two 150 ml portions of 1 N hydrochloric acid, 50 ml of water and 100 ml of 2% sodium hydroxide. The basic layer is acidified with 10 N hydrochloric acid and the resulting mixture is extracted with three 50 ml portions of diethyl ether. Evaporation of the ether affords an oil which is triturated with 50 ml hexane to give 1.65 g 2-(1-carbobenzyloxy-4-hydroxypiperidin-4-yl)-2-methylpropionic acid, an oil.

Quelle