To a solution of 2-(4-fluorophenyl)-2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indole-8-carboxylic acid (24, 50 mg, 0.16 mmol) in DMF (2.0 mL), HATU (75 mg, 0.2 mmol), 1-(pyridin-3-ylmethyl)piperidin-4-amine dihydrochloride (48 mg, 0.16 mmol) and triethylamine (150 μL, 110 mg, 1.1 mmol) were added. The resulting reaction mixture was allowed to stir at room temperature overnight, poured into saturated sodium bicarbonate solution (10 mL) to give a precipitate, filtered and dried under vacuum overnight. Trituration with ethyl ether provided 2-(4-fluorophenyl)-N-(1-(pyridin-3-ylmethyl)piperidin-4-yl)-2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indole-8-carboxamide (Compound 36) as a pale yellow solid (57 mg, 73%). 1H NMR (DMSO-d6, 300 MHZ) 11.08 (s, 1H), 8.49 (d, J=1.4 Hz, 1H), 8.45 (dd, J=4.8, 1.5 Hz, 1H), 8.03 (d, J=8.0 Hz, 1H), 8.02 (s, 1H), 7.70 (dt, J=7.7, 1.8 Hz, 1H), 7.56 (dd, J=8.4, 1.5 Hz, 1H), 7.35 (dd, J=7.7, 4.7 Hz, 1H), 7.28 (d, J=8.3 Hz, 1H), 7.06 (d, J=5.0 Hz, 2H), 7.05 (d, J=3.3 Hz, 2H), 4.37 (s, 2H), 3.87-3.72 (m, 1H), 3.63 (t, J=5.2 Hz, 2H), 3.52 (s, 2H), 2.92-2.78 (m, 4H), 2.12-2.00 (m, 2H), 1.80 (d, J=10.5 Hz, 2H), 1.61 (qd, J=11.7, 3.0 Hz, 2H) ppm; MS (ES) 484 (M+H).
