Reaction Steps
A solution of 5-nitroindole (38) (0.5 g, 3.083 mmol) in glacial acetic acid (10 mL) was treated with tropinone (0.85 g, 6.617 mmol), followed by 2 M H3PO4 in glacial acetic acid (5 mL) at 100° C. and the resulting solution was stirred at same temperature for 24 h. The reaction was brought to room temperature, poured in to ice-cold 10% NH4OH solution (50 mL) and product was extracted into CH2Cl2 (2 25 mL). The combined CH2Cl2 layer was washed with brine (15 mL) and dried (Na2SO4). The solvent was evaporated and crude material was purified by column chromatography on silica gel (2 M NH3 in methanol: CH2Cl2, 1:9) to obtain compound 89 (0.27 g, 31%) as a solid. mp 234-236° C.; 1H NMR (DMSO-d6) δ 1.51-1.60 (m, 1H), 1.79-1.86 (m, 1H), 1.95-2.14 (m, 4H), 2.32 (s, 3H), 2.76-2.83 (m, 1H), 3.43 (t, 1H, J=5.4 Hz), 6.31 (d, 1H, J=5.1 Hz), 7.54 (d, 1H, J=8.7 Hz), 7.61 (s, 1H), 8.01 (dd, 1H, J=2.1, 9.0 Hz), 8.68 (d, 1H, J=2.4 Hz), 11.86 (s, 1H); ESI-MS m/z (%): 284 (MH+, 100). N-(3-(8-Methyl-8-azabicyclo[3.2.1]oct-3-en-3-yl)-1H-indol-5-yl)thiophene-2-carboximidamide (90): A solution of compound 89 (0.25 g, 0.882 mmol) in dry ethanol (10 mL) was treated with Pd—C (0.025 g) and purged with hydrogen gas. The reaction was stirred under hydrogen atm. (balloon pressure) for overnight (14 h). The solid was filtered off using celite bed and washed with ethanol (2 5 mL). The combine d ethanol layer was treated with thiophene-2-carboximidothioic acid methyl ester hydroiodide (0.5 g, 1.764 mmol) at room temperature and stirred for 24 h. Ethanol was evaporated and crude material was basified with sat. NaHCO3 solution (20 mL) and product was extracted into CH2Cl2 (2 25 mL). The combined CH2Cl2 layer was washed with brine (15 mL) and dried (Na2SO4). The solvent was evaporated and crude was purified by column chromatography on silica gel (2 M NH3 in methanol: CH2Cl2, 1:9) to obtain compound 90 (0.14 g, 44%) as a solid. mp 93-95° C.; 1H NMR (DMSO-d6) δ 1.60-1.65 (m, 1H), 1.84-1.90 (m, 1H), 2.02-2.26 (m, 4H), 2.41 (s, 3H), 2.83-2.89 (m, 1H), 3.46-3.55 (m, 1H), 6.20 (brs, 2H), 6.67 (d, 1H, J=7.8 Hz), 7.10 (s, 1H), 7.23-7.31 (m, 3H), 7.60-7.72 (m, 2H), 10.99 (s, 1H); ESI-MS m/z (%): 363 (MH+, 65), 182 (100), 119 (48); ESI-HRMS calculated for C21H23N4S (MH+), Calculated: 363.1633; Observed: 363.1637.
