IR spectra were run in
KBr pellets on a Perkin–Elmer 157 spectrometer. 1H NMR spectra were recorded in CDCl3 or DMSO on a Bruker–Varian 300 MHz FT NMR spectrometer using TMS as internal standard. Purity of the compounds was checked by TLC on silica gel G plates see more and the spots were located by exposure to iodine vapors. The characterization data of the compounds is given in Tables 1 and 2. 3,5-Dimethyl-2,4-diethoxy carbonyl pyrrole (1) (0.05 mol), hydrazine hydrate (1.0 mL, 99%), and ethanol (20 mL). The completion of reaction was checked by thin layer chromatography. The mixture was evaporated to its half and left over night. The product precipitated was filtered, washed with water, dried and crystallized from ethanol. Yield 70%: M.P.216 °C: IR (KBr): 3153 (NH), 1621 (CONH), 1712 (COOC2H5), 1322 (–CH3): 1NMR (300 MHz find protocol DMSO) δ 7.82–7.91 (m, 3H, CONHNH2), 8.9 (1H, s, Pyrrole–NH). A mixture of compounds 2-(3′,5′-Dimethyl-4′-ethoxy
carbonyl pyrrole) acid hydrazide (2) (0.01 mol), phenylisocynate (0.01 mol) and ethanol (25.0 mL) was refluxed for 8 h. The resulting mixture was evaporated to its half and the mixture was left for 48 h. The separated solid was filtered and crystallized from aq. ethanol. Yield. 85%, M.P.197 °C, IR (KBr): 3240 (NH), 1685 (CONH), 1595 (ArH), 1360 (–CH3), 1700 cm−1 (COOC2H5), 1H NMR (300 MHz Dipeptidyl peptidase DMSO), δ 8.2 (1H, s, Pyrrole-NH), 7.1–7.8 (3H, m, CONHNHCONH). Yield 70%, M.P. 205 °C; IR (KBr); 3337 cm−1 (NH), 1660 cm−1 (CONH), 1565 cm−1 (ArH), 1763 (COOC2H5) 1345 cm−1 (–CH3); 1H NMR (300 MHz DMSO), δ 2.7 (6H, s, 2 × CH3), 8.3 (1H, s, NH), 7.7 (3H, m, CONHNHCONH). Yield 65%, M.P. 180 °C; IR (KBr); 3338 (NH), 1683 (CONH), 1547 (ArH), 748 cm−1 (C–Cl), 1H NMR (300 MHz DMSO), δ 3.1 (6H, s, 2 × CH3), 6.1–8.0
(Ar–H), 8.1 (NH), 7.7 (3H, m, CONHNHCONH). Yield 88%, M.P. 218 °C; IR (KBr); 3345 (NH), 1687 (CONH), 1557 (ArH), 768 cm−1 (C–Cl), 1H NMR (300MHzDMSO), δ 3.1 (6H, s, 2 × CH3), 7.92 (1H, s, NH), 8.2 (3H, m, CONHNHCONH). Yield 80%, M.P. 120 °C; IR (KBr); 3335 (NH), 1683 (CONH), 1540 (ArH), 1537 cm−1 (C–NO2), 1H NMR (300 MHz DMSO), δ 3.1 (6H, s, 2 × CH3), 8.61 (1H, s, NH), 8.5 (3H, m, CONHNHCONH). Yield 60%, M.P. 198 °C; IR (KBr); 3330 (NH), 1683 (CONH), 1577 (ArH), 1472 cm−1 (C–NO2), 1H NMR (300 MHz DMSO), δ 3.1 (6H, s, 2 × CH3), 7.1 (1H, s, NH), 6.9 (3H, m, CONHNHCONH). Yield 55, M.P. 257 °C; IR (KBr); 3335 (NH), 1673 (CONH), 1567 (ArH), 1532 cm−1 (C–NO2), 1H NMR (300 MHz DMSO), δ 3.1 (6H, s, 2 × CH3), 8.21 (1H,s, NH), 7.8 (3H, m, CONHNHCONH). To a solution of 2-(3′,5′-dimethyl-4′-ethoxy carbonyl pyrrole)-1-phenyl-isosemi-carbazide (3) (2g) in 25 ml of dry methanol was added of (4 N, 3 mL), sodium hydroxide solution and refluxed for 3 h and kept at room temperature for 24 h.