Reaction #2045043

Reaction equation

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

dioxane

triphosgene

dioxane

→

57

Yield 37.2%

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

Yield 37.2%

Conditions

Workup

1. 1
   Temperatureand cooled below 20° C
2. 2
   Temperaturemaintained for 3 hrs
3. 3
   workup.DISTILLATIONThe condenser was arranged for distillation and solvent
4. 4
   Otherremoved by distillation at one atm. until the volume of the reaction mixture
5. 5
   workup.ADDITIONFresh dry dioxane (50 ml) was added
6. 6
   workup.DISTILLATIONsolvents distilled off under vacuum
7. 7
   OtherThe residue was re-evaporated twice from dry dioxane

Procedure

2-(4-Aminophenoxy)propionic acid-2-[2-(4-aminophenoxy)acetoxy]ethyl ester 56 (5.2 g, 13.9 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 3 hrs. The condenser was arranged for distillation and solvent removed by distillation at one atm. until the volume of the reaction mixture was reduced to approx. one third. Fresh dry dioxane (50 ml) was added and solvents distilled off under vacuum. The residue was re-evaporated twice from dry dioxane to give 57 (2.2 g, 37.2%) as a light yellow syrup.

Source