Reacción #52039

Ecuación de reacción

BOC-L-valine

acetamidoxime

dicyclohexylcarbodiimide

→

(S)-5-(1-amino-2-methylpropyl)-3-methyl-1,2,4-oxadiazole

Disolventes

dichloromethane

pyridine

dichloromethane

Condiciones de reacción

Tratamiento posterior

1. 1
   OtroAfter 1 hour the white solid which had formed
2. 2
   Otrowas removed by filtration
3. 3
   Concentraciónthe filtrate concentrated under reduced pressure
4. 4
   workup.DISSOLUTIONThe residue was dissolved in pyridine (15 mL)
5. 5
   Temperaturathe mixture heated
6. 6
   Temperaturaat reflux for 1 hour
7. 7
   OtroThe pyridine was evaporated under reduced pressure
8. 8
   Otrothe residue partitioned between ethyl acetate and water
9. 9
   LavadoThe organic phase was washed several times with water
10. 10
    Secadodried over magnesium sulfate
11. 11
    Concentraciónconcentrated
12. 12
    OtroThe residue was chromatographed on silica gel using 10% ethyl acetate in hexanes
13. 13
    Lavadoto elute the product (0.62 g, 25%) as a white solid

Procedimiento

A solution of BOC-L-valine (4.34 g, 20.0 mmol) in dichloromethane (20 mL) was cooled to 0° C. and treated dropwise with a solution of dicyclohexylcarbodiimide (2.06 g, 10.0 mmol) in dichloromethane (5 mL). After 1 hour the white solid which had formed was removed by filtration and the filtrate concentrated under reduced pressure. The residue was dissolved in pyridine (15 mL) and treated with acetamidoxime (488 mg, 6.6 mmol) in pyridine (5 mL) and the mixture heated at reflux for 1 hour. The pyridine was evaporated under reduced pressure and the residue partitioned between ethyl acetate and water. The organic phase was washed several times with water, dried over magnesium sulfate and concentrated. The residue was chromatographed on silica gel using 10% ethyl acetate in hexanes to elute the product (0.62 g, 25%) as a white solid.

Fuente