Reacción #725915

Ecuación de reacción

(4-Aminophenoxy)acetic acid 2-[2-(4-aminophenoxy)acetoxy]ethyl ester

(4-Amino-phenoxy)-acetic acid-2-[2-(4-amino-phenoxy)-acetoxy]-ethyl ester

dioxane

triphosgene

dioxane

→

44

Rendimiento 44.2%

(4-Isocyanatophenoxy)acetic acid-2-[2-(4-isocyanatophenoxy)acetoxy]ethyl ester

Rendimiento 44.2%

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturaand cooled to below 20° C
2. 2
   Temperaturamaintained for 2½ hours
3. 3
   workup.DISTILLATIONThe condenser was then arranged for distillation and solvent
4. 4
   Otroremoved by distillation at atmospheric pressure until the volume of the reaction mixture
5. 5
   workup.ADDITIONFresh dry dioxane (50 ml) was added
6. 6
   workup.DISTILLATIONthe solvents were distilled off under vacuum
7. 7
   OtroThe residue was re-evaporated two times from dry dioxane
8. 8
   Otroto give crude 44
9. 9
   OtroCrude 44 was recrystallised from a mixture of toluene:hexane (1:3)

Procedimiento

(4-Aminophenoxy)acetic acid 2-[2-(4-aminophenoxy)acetoxy]ethyl ester 43 (5 g, 14.3 mmol) was dissolved in dry dioxane (80 ml) under nitrogen atm. and cooled to below 20° C. A solution of triphosgene (7 g, 23.6 mmol) in dry dioxane (20 ml) was added drop wise. The mixture was heated slowly to 75-80° C. and maintained for 2½ hours. The condenser was then arranged for distillation and solvent removed by distillation at atmospheric pressure until the volume of the reaction mixture was reduced to approximately one third. Fresh dry dioxane (50 ml) was added and the solvents were distilled off under vacuum. The residue was re-evaporated two times from dry dioxane to give crude 44. Crude 44 was recrystallised from a mixture of toluene:hexane (1:3) to give pure 44 (2.6 g, 44.2%) as a white powder. M.p: 96-98° C.

Fuente