Urea → HCID 10778555, compound

Participants

Reaction Steps

2.00 g (11 mmoles) 4-methylglutamic acid and 1.95 g (13 mmoles) phthalic anhydride were heated for 6 hours under reflux in 15 ml of dry pyridine. After removing the solvent by distillation, the residue was heated to boiling for 1 hour in 10 ml acetic anhydride. The solid which precipitated on cooling was filtered off under suction and the filtrate was concentrated. After treating the filtrate with ether, the precipitate which formed was filtered off under suction and the purified precipitates were recrystallised from absolute toluene. 2.00 g (7 mmoles) of the crystalline material and 0.23 g (3.8 mmoles) urea were well mixed and 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 6 ml ethanol in succession. The precipitated solid was filtered off under suction and recrystallised from DMF/water. 1.35 g (67% theoretical) 2-(5-methyl-2,6-dioxo-piperidin-3-yl)-1,3-dihydro-2H-isoindole-1,3-dione (1) were obtained, with a melting point of 270 to 272° C.

Provenance & Evidence