Dimethylamine → 6-(Dimethylamino)-7-methyl-2,3-dihydro-1H-pyrrolo [1,2-a]benzimidazole-5,8-dione

Participants

Reaction Steps

To a solution of 50 mg (0.24 mmol) of 26 in 3 mL of dry DMF, chilled to 0° C., was added an excess of methanolic dimethylamine. After the addition, the reaction mixture was stirred at room temperature for about 30 min and then the solvent was evaporated in vacuo. The residue was chromatographed on silica gel employing chloroform as the eluant. The blue-colored 27 was obtained in 42 mg (71%) yield. An analytical sample was prepared by dissolving the residue in a small amount of chloroform, adding hexane, and then chilling the mixture overnight in the refrigerator: mp 158° C. dec; TLC (chloroform/methanol[90:10]), Rf =0.56, IR(KBr pellet) 1675, 1659, 1623, 1524, 1314, 1067 cm-1 ; 1H NMR (CDCl3) δ4.16 (2 H, t, J~7 Hz, C(1) methylene), 3.04 (6 H, s, dimethylamino), 2.87 (2 H, t, J~7 Hz, C(3) methylene), 2.64 (2 H, quintet, J~7 Hz, C(2) methylene); 1.93 (3 H, s, 7-methyl); mass spectrum (EI mode) m/z 245 (P+), 230 (P+ -CH3), 217 (P+ -CO). Anal. Calcd for C13H15N3O2.0.25: C, 62.50; H, 6.15; N, 16.82. Found: C, 62.78; H, 6.32; N, 16.64.

Provenance & Evidence