Urea → HCID 10640444, compound

Participants

Reaction Steps

3.00 g (12 mmoles) 4-phenylglutamic acid and 2.12 g (14 mmoles) phthalic anhydride were heated for 6 hours under reflux in 40 ml of dry pyridine. After removing the solvent by distillation, the residue was taken up in 50 ml of 5% HCl and extracted with ethyl acetate. The organic phase was washed with water, decolourised with activated carbon and dried over sodium sulphate. After removing the solvent by distillation, the residue was heated under reflux for 1 hour in 40 ml acetic anhydride. The solution was subsequently concentrated and treated with ether. The precipitate formed was filtered off under suction and was recrystallised from dry toluene. 2.00 g (6 mmoles) of the crystalline material and 0.19 g (3 mmoles) urea were fused on an oil bath at about 200° C. for 30 minutes. The solidified melt was heated briefly to boiling, with 4 ml acetic anhydride and 8 ml ethanol in succession. The precipitated solid was recrystallised from DMF/water. 0.80 g (40% theoretical) 2-(5-phenyl-2,6-dioxo-piperidin-3-yl)-1,3-dihydro-2H-isoindole-1,3-dione (2) were obtained, with a melting point of 228 to 231° C.

Provenance & Evidence