Reaction #931702

Reaction equation

dihexylamine

1-benzyl-1,2-dihydro-2-oxoquinoxaline-3-carboxylic acid

triethylamine

ethyl chlorocarbonate

→

N,N-dihexyl-1-benzyl-1,2-dihydro-2-oxoquinoxaline-3-carboxamide

Solvents

tetrahydrofuran

Conditions

Workup

1. 1
   Temperatureafter cooling to —40° C.
2. 2
   workup.STIRRINGAfter stirring at −40° C. for an hour
3. 3
   Temperaturethe temperature was raised to room temperature over an hour
4. 4
   workup.STIRRINGby stirring at room temperature overnight
5. 5
   ConcentrationThe reaction mixture was concentrated under reduced pressure
6. 6
   workup.ADDITIONthe residue, after addition of ethyl acetate
7. 7
   Washwas washed with water, 1N hydrochloric acid
8. 8
   Dryinga saturated aqueous sodium bicarbonate solution and a saturated aqueous sodium chloride solution, and dried over anhydrous sodium sulfate
9. 9
   OtherAfter removal of the drying agent
10. 10
    Filtrationby filtration
11. 11
    Concentrationthe filtrate was concentrated under reduced pressure
12. 12
    OtherThe residue was purified by chromatography (silica gel; Wakogel C200 (manufactured by Wako Pure Chemicals), developing solvent; chloroform)
13. 13
    Otherrecrystallized from hexane

Procedure

In 30 ml of tetrahydrofuran were dissolved 0.50 g of 1-benzyl-1,2-dihydro-2-oxoquinoxaline-3-carboxylic acid and 0.87 ml of triethylamine, and after cooling to —40° C., 0.19 ml of ethyl chlorocarbonate was added dropwise over 5 minutes. After stirring at −40° C. for 10 minutes, 0.46 ml of dihexylamine was added dropwise over 5 minutes. After stirring at −40° C. for an hour, the temperature was raised to room temperature over an hour, followed by stirring at room temperature overnight. The reaction mixture was concentrated under reduced pressure, and the residue, after addition of ethyl acetate, was washed with water, 1N hydrochloric acid, a saturated aqueous sodium bicarbonate solution and a saturated aqueous sodium chloride solution, and dried over anhydrous sodium sulfate. After removal of the drying agent by filtration, the filtrate was concentrated under reduced pressure. The residue was purified by chromatography (silica gel; Wakogel C200 (manufactured by Wako Pure Chemicals), developing solvent; chloroform) and recrystallized from hexane to give 0.53 g of N,N-dihexyl-1-benzyl-1,2-dihydro-2-oxoquinoxaline-3-carboxamide.

Source