6,7-Dihydro-1H,5H-pyrrolo[2,3-c]azepine-4,8-dione

129053-84-5

72908-87-3

GENERAL METHOD: Phosphorus pentoxide (2.02 g, 14.23 mmol) was dissolved in methanesulfonic acid (13 mL, 195.8 mmol), heated to 80 °C and stirred until homogeneous. Subsequently, 3-[(1H-pyrrole-2-carbonyl)-amino]propanoic acid (3.24 g, 17.78 mmol) was added, the reaction was continuously stirred and the progress of the reaction was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the reaction mixture was quenched with ice water and extracted several times with ethyl acetate. The organic phases were combined, dried over anhydrous magnesium sulfate (MgSO4) and concentrated under reduced pressure to afford 6,7-dihydropyrrolo[2,3-c]azepine-4,8(1H,5H)-dione as a white solid (1.58 g, 54% yield). The product was characterized by the following data: melting point 280-282 °C; IR (cm-1) 3222, 2931, 1659, 1634; 1H NMR (δ, ppm) 2.70 (2H, m), 3.35 (2H, m), 6.55 (1H, d, J = 2.7 Hz), 6.99 (1H, d, J = 2.7 Hz), 8.34 (1H, t, J = 4.7 Hz), 12.18 (1H, br s); 13C NMR (δ, ppm) 36.9, 43.8, 109.9, 122.7, 123.9, 128.3, 162.6, 194.7; LRMS (ES+) m/z 186.8 [M + Na]+; HRMS (ES+) 165.0657 ([M + H] +, calculated value 165.0664 for C8H9N2O2).