反应详情

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.

1. customAfter removing the solvent
2. distillationby distillation
3. temperaturethe residue was heated
4. customThe solid which precipitated
5. temperatureon cooling
6. filtrationwas filtered off under suction
7. concentrationthe filtrate was concentrated
8. additionAfter treating the filtrate with ether
9. customthe precipitate which formed
10. filtrationwas filtered off under suction
11. customthe purified precipitates
12. customwere recrystallised from absolute toluene
13. waitwere fused on an oil bath at about 200° C. for 30 minutes
14. temperatureThe solidified melt was heated briefly
15. filtrationThe precipitated solid was filtered off under suction
16. customrecrystallised from DMF/water