Reaction Steps
2,3,5,6-Tetrafluorophenyl trifluoroacetate (2.6 g, 10 mmol, H. B. Gamper, M. W. Reed, T. Cox, J. S. Virosco, A. D. Adams, A. A. Gall, J. K. Scholler and R. B. Meyer, Jr. Nucleic Acids Res., 1993, Vol. 21, No.1, 145-150) was added dropwise to a solution of 3-carbamoyl-1,2-dihydro-3H-pyrrolo[3,2-e]indole-7-carboxylic acid (1.4 g, 6.1 mmol, D. L. Boger, R. S. Coleman, and B. J. Invergo. J. Org. Chem., 1987, Vol.52, 1521-1530) and triethylamine (1.4 ml, 10 mmol) in 15 ml of anhydrous DMF. After 1 hr, the reaction mixture was concentrated under vacuum (0.2 mm). The residue was triturated with 2 ml of dry dichloromethane. Ethyl ether (50 ml) was added and the mixture was left at 0° C. overnight. The precipitate was collected by filtration on sintered glass funnel, washed first with 50% ether/CH2Cl2 (10 ml), then with ether (50 ml) and dried in vacuo. The product was obtained as a yellow solid (1.8 g, 75%): 1H NMR (Me2SO-d6, 200 MHz, ppm) 12.32 (s, 1H, NH), 8.13 (d, 1H, J=9 Hz, C4-H), 8.01 (m, 1H, C6F4H), 7.41 (s, 1H, C8-H), 7.26 (d, 1H, J=9 Hz, C5-H), 6.17 (s, 2H, CONH2), 3.99 (t, 2H, J=9 Hz, NCH2CH2), 3.30 (t, 2H, J=9 Hz, NCH2CH2). Anal. Calcd. for C18H11 N3O3F4 ×2H2O: C, 50.3; H, 3.52; N, 9.7. Found; C, 50.81; H, 3.60; N, 9.95.
