Reacción #867

Ecuación de reacción

water

HOBt

HCl dioxane

N-t-butoxycarbonyl-α,α-diethylglycine (S)-α-ethylbenzylamide

triethylamine

β-benzyl-N-benzyloxycarbonyl-L-aspartate

→

α-L-aspartyl-α,α-diethylglycine (S)-α-ethylbenzylamide

Rendimiento 29.3%

Condiciones de reacción

Tratamiento posterior

1. 1
   ConcentraciónThe reaction mixture was concentrated under reduced pressure, 30 ml of ether
2. 2
   workup.ADDITIONwas added to the residue
3. 3
   Concentraciónthis was again concentrated
4. 4
   workup.DISSOLUTIONThe residue was dissolved in 25 ml of methylene chloride
5. 5
   TemperaturaUnder cooling
6. 6
   workup.STIRRINGthese were stirred for one hour
7. 7
   Temperaturaunder cooling
8. 8
   Otroovernight
9. 9
   Otroat room temperature
10. 10
    ConcentraciónThe reaction mixture was concentrated under reduced pressure and 50 ml of aqueous 5% citric acid
11. 11
    workup.ADDITIONwere added
12. 12
    ExtracciónThe resulting residue was extracted two times each with 50 ml of ethyl acetate
13. 13
    Lavadowashed with 20 ml of water, 25 ml of aqueous 5% sodium hydrogencarbonate and 20 ml of brine, in that order
14. 14
    SecadoThe resulting organic layer was dried with anhydrous magnesium sulfate
15. 15
    Filtraciónfiltered
16. 16
    Concentraciónthe resulting filtrate was concentrated under reduced pressure
17. 17
    workup.DISSOLUTIONThe residue was dissolved in 30 ml of methanol
18. 18
    workup.ADDITION0.30 g of 10% Pd-carbon (water content 50) was added
19. 19
    workup.ADDITION40 ml of water was added to this, the catalyst
20. 20
    Otrowas removed by filtration
21. 21
    Concentraciónthe resulting filtrate was concentrated to about 1/4
22. 22
    OtroThis was then stored in a refrigerator overnight
23. 23
    OtroThe crystal thus precipitated
24. 24
    Otrowas removed by filtration
25. 25
    Otrodried

Procedimiento

19 ml of 4N-HCl/dioxane solution were added to 1.31 g (3.76 mmols) of N-t-butoxycarbonyl-α,α-diethylglycine (S)-α-ethylbenzylamide, and the mixture was stirred at room temperature for one hour. The reaction mixture was concentrated under reduced pressure, 30 ml of ether was added to the residue, and this was again concentrated. The residue was dissolved in 25 ml of methylene chloride, and 0.55 ml (4.13 mmols) of triethylamine and 1.48 g (4.13 mmols) of β-benzyl-N-benzyloxycarbonyl-L-aspartate were added thereto. Under cooling, 0.79 g (4.13 mmols) of water-soluble carbodiimide hydrochloride and 0.51 g (3.76 mmols) of HOBt were added thereto, and these were stirred for one hour under cooling and then overnight at room temperature. The reaction mixture was concentrated under reduced pressure and 50 ml of aqueous 5% citric acid were added. The resulting residue was extracted two times each with 50 ml of ethyl acetate and then washed with 20 ml of water, 25 ml of aqueous 5% sodium hydrogencarbonate and 20 ml of brine, in that order. The resulting organic layer was dried with anhydrous magnesium sulfate and filtered, and the resulting filtrate was concentrated under reduced pressure. The residue was dissolved in 30 ml of methanol, 0.30 g of 10% Pd-carbon (water content 50) was added thereto, and the mixture was reduced under hydrogen. 40 ml of water was added to this, the catalyst was removed by filtration, and the resulting filtrate was concentrated to about 1/4. This was then stored in a refrigerator overnight. The crystal thus precipitated was removed by filtration and dried to obtain 0.40 g (1.10 mmols) of α-L-aspartyl-α,α-diethylglycine (S)-α-ethylbenzylamide.

Fuente