1,4-Dioxane → Ethane-1,2-diyl bis(2-(4-isocyanatophenoxy)acetate)

Participants

Reaction Conditions

Reaction Steps

(4-Aminophenoxy)-acetic acid 2-[2-(4-aminophenoxy)-acetoxy]-ethyl ester 25 (5 g, 14.3 mmol) were 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 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 solvent was distilled off under vacuum. The residue was re-evaporated two times from dry dioxane to give crude 26. Crude 26 was recrystallised from a mixture of toluene:hexane (1:3) to give pure 26 (2.6 g, 44.2%) as a white powder with an m.p. between 96-98° C.

Provenance & Evidence