反应详情

1H-Imidazole-2,4-dicarboxylic acid 2-benzyl ester 4-ethyl ester was prepared in a manner substantially similar to that described by Branco, P. S.; Prabhakar, S.; Lobo, A. M.; Williams, D. Tetrahedron, 1992, 48, 6335. To a solution of 1H-imidazole-2,4-dicarboxylic acid 2-benzyl ester 4-ethyl ester (380 mg, 1.4 mmol) in EtOH (10 mL) was added Pd/C (10%) (40 mg) under N2 atmosphere. The suspension was then treated with hydrogen under 50 psi for 3 hours. The catalyst was removed by filtration through Celite® and the filtrate was evaporated. To a solution of the crude acid (140 mg, 0.76 mmol) in DMA (2 mL) was added CDI (140 mg, 0.86 mmol). The mixture was stirred at ambient temperature for 1 hour and then 2,5-dihydro-1H-pyrrole (110 mg, 1.59 mmol) was added. After stirring at ambient temperature for 2 hours, the reaction mixture was poured into water (5 mL). The aqueous solution was extracted with EtOAc (2×10 mL) and the combined organic layers dried over MgSO4, filtered, and evaporated. The crude product was purified by flash column eluting with 50% EtOAc in hexane to afford the title compound as a white solid (110 mg, 61%). MS (ES+): m/e=236.2 (M+H); Rt=2.04 minutes.

1. customThe catalyst was removed by filtration through Celite®
2. customthe filtrate was evaporated
3. stirringAfter stirring at ambient temperature for 2 hours
4. extractionThe aqueous solution was extracted with EtOAc (2×10 mL)
5. dry with materialthe combined organic layers dried over MgSO4
6. filtrationfiltered
7. customevaporated
8. customThe crude product was purified by flash column
9. washeluting with 50% EtOAc in hexane