To a stirred solution of phenyl 2-(6-amino-8-fluoro-3,4-dihydroquinolin-1(2H)-yl)ethyl(methyl)carbamate (426 mg, 1.241 mmol) in ethanol (12 ml) was added methyl thiophene-2-carbimidothioate hydroiodide (708 mg, 2.481 mmol). The reaction mixture was stirred at room temperature overnight under argon. The reaction mixture was then diluted with water and sodium carbonate, then extracted with dichloromethane (3×). The combined organics were dried, filtered and concentrated, then chromatographed in 40-100% ethyl acetate in hexanes, giving the desired phenyl 2-(8-fluoro-6-(thiophene-2-carboximidamido)-3,4-dihydroquinolin-1(2H)-yl)ethyl(methyl)carbamate 52 (422 mg, 0.933 mmol, 75% yield). 1H NMR (DMSO-d6) δ 7.74-7.71 (m, 1H); 7.59-7.57 (m, 1H); 7.41-7.36 (m, 2H); 7.23-7.18 (m, 1H); 7.14-7.07 (m, 3H); 6.50-6.42 (m, 3H); 6.37 (s, 1H); 3.62 (t, J=6 Hz, 1H); 3.51 (t, J=6 Hz, 1H); 3.30 (t, J=6 Hz, 1H); 3.23 (t, J=6 Hz, 1H); 3.15-3.09 (m, 2H); 3.09, 2.97 (2s, 3H); 2.69 (t, J=6 Hz, 2H); 1.83-1.75 (m, 2H). EI-MS (m/z, %): 452 (M+, 8); 288 (60); 179 (100).
