Reaction #2045038

Reaction equation

2-(4-Aminophenoxy)propionic acid-2-[2-(4-aminophenoxy)propionyloxy]ethyl ester

dioxane

triphosgene

dioxane

→

51

Yield 66.5%

2-(4-Isocyanatophenoxy)propionic acid-2-[2-(4-isocyanatophenoxy)propionyloxy]ethyl ester

Yield 66.5%

Conditions

Workup

1. 1
   Temperatureand cooled below 20° C
2. 2
   Temperaturemaintained for 2½ hours
3. 3
   workup.DISTILLATIONThe condenser was then arranged for distillation and solvent
4. 4
   Otherremoved by distillation at atmospheric pressure until the volume of reaction mixture
5. 5
   workup.ADDITIONFresh dry dioxane (50 ml) was added
6. 6
   workup.DISTILLATIONthe solvents were distilled off under vacuum
7. 7
   OtherThe residue was re-evaporated two times from dry dioxane

Procedure

2-(4-Aminophenoxy)propionic acid-2-[2-(4-aminophenoxy)propionyloxy]ethyl ester 50 (5.3 g, 13.6 mmol) was dissolved in dry dioxane (80 ml) under nitrogen atm. and cooled below 20° C. A solution of triphosgene (7 g, 23.6 mmol) in dry dioxane (20 ml) was added dropwise. 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 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 pure 51 (4 g, 66.5%) as a light brown liquid.

Source