Reaction #170990

Reaction equation

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

dioxane

triphosgene

dioxane

→

40

Yield 37.2%

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

Yield 37.2%

Conditions

Workup

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

Procedure

2-(4-Aminophenoxy)-propionic acid 2-[2-(4-aminophenoxy)-acetoxy]-ethyl ester 39 (5.2 g, 13.9 mmol) was dissolved in dry dioxane (80 ml) under nitrogen atmosphere 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 main-tained for 3 hrs. A 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 solvent was distilled off under vacuum. The residue was re-evaporated two times from dry dioxane to give 40 (2.2 g, 37.2%) as a light yellow syrup.

Source