Reaktion #44929

Reaktionsgleichung

EtOAc

dimethylaminoethanol

6-hydroxy-2,5,7,8-tetramethyl-chroman-2-carboxylic acid

dicyclohexylcarbodiimide

→

6-Hydroxy-2,5,7,8-tetramethyl-chroman-2-carboxylic acid 2-dimethylaminoethyl ester

Ausbeute 37.3%

Lösungsmittel

hexane

CH2Cl2

CH2Cl2

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONwas added to the mixture
2. 2
   Sonstigeto form a cloudy suspension
3. 3
   workup.STIRRINGThe solution was stirred at room temperature overnight
4. 4
   Filtrationthe resulting white suspension was filtered
5. 5
   Sonstigeto give a clear solution
6. 6
   WaschenThe solution was washed three times with water
7. 7
   Sonstigethe organic layer was collected
8. 8
   Trocknendried over anhydrous sodium sulfate
9. 9
   SonstigeThe drying agent was removed by filtration
10. 10
    Einengenthe filtrate was concentrated by rotary evaporation
11. 11
    Sonstigeyielding a viscous, yellowish oil
12. 12
    SonstigeThe residue obtained
13. 13
    WaschenThe column was eluted with EtOAc/hexane (1:1
14. 14
    Sonstigev/v) to remove the less polar impurity
15. 15
    Waschento elute the desired product from the column

Vorschrift

To a stirred solution of 6-hydroxy-2,5,7,8-tetramethyl-chroman-2-carboxylic acid (2.6 g, 10 mmol) in 80 mL of CH2Cl2 was added dicyclohexylcarbodiimide (2.2 g, 10 mmol). After stirring for 5 min, dimethylaminoethanol (0.93 g, 10 mmol) dissolved in 10 mL of CH2Cl2 was added to the mixture to form a cloudy suspension. The solution was stirred at room temperature overnight, and the resulting white suspension was filtered to give a clear solution. The solution was washed three times with water, and the organic layer was collected and dried over anhydrous sodium sulfate. The drying agent was removed by filtration and the filtrate was concentrated by rotary evaporation, yielding a viscous, yellowish oil. The residue obtained was loaded to a silica gel column with a mixed solvent of EtOAc and hexane (1:1, v/v). The column was eluted with EtOAc/hexane (1:1, v/v) to remove the less polar impurity. Subsequently, a mixed solvent of CH2Cl2/MeOH/NH4OH (90:10:0.5, v/v/v) was used to elute the desired product from the column. 1.2 g of 6-Hydroxy-2,5,7,8-tetramethyl-chroman-2-carboxylic acid 2-dimethylaminoethyl ester were obtained as a viscous yellowish oil, which solidified upon standing at room temperature. MS: m/z=322.2 (M+H+). 1H NMR (CDCl3, 300 Hz) 4.19 (t, J=5.8 Hz, 2H), 2.52-1.80 (m, 4H), 2.48 (t, 2H), 2.20 (s, 6H), 2.18 (s, 3H), 2.16 (s, 3H), 2.06 (s, 3H), 1.61 (s, 3H). 13C NMR (CDCl3, 75 Hz) 173.9, 145.6, 145.4, 122.5, 121.6, 118.8, 116.9, 77.0, 63.3, 57.5, 45.7, 30.6, 25.4, 21.0, 12.3, 11.9, 11.3.

Quelle