Part A. 3-chloro-4-fluorophenyl hydrazine (5.00 g, 31.14 mmol) and 1-(4-iodophenyl)-4-(trifluoroacetyl)-2,3-piperidinedione (12.8 g, 31.14 mmol) were added together with 120 mL of ethanol and 4 mL of hydrochloric acid (12 M). The mixture was stirred at reflux under N2 for overnight. The reaction was cooled down to rt. The solvents were removed, and the residue was dissolved in EtOAc (200 mL) and washed with water (100 mL×2) and brine (50 mL). It was then dried over Na2SO4 and concentrated. The residue was purified via flash chromatography on silica gel using 4:1 hexane:ethylacetate to give 1-(3-chloro-4-fluorophenyl)-6-[4-iodophenyl]-3-(trifluoromethyl)-1,4,5,6-tetrahydro-7H-pyrazolo[3,4-c]pyridine-7-one as a brown solid (12.5 g, 75% yield). LRMS (AP+): 536.1 (M+H)+. 1H NMR (CDCl3) δ 7.72 (d, 2H), 7.67–7.64 (m, 1H), 7.49–7.44 (m, 1H), 7.19 (t, 3H), 7.06 (d, 2H), 4.12 (t, 2H), 3.17 (t, 2H). Part B. 1-(3-chloro-4-fluorophenyl)-6-[4-iodophenyl]-3(trifluoromethyl)-1,4,5,6-tetrahydro-7H-pyrazolo[3,4-c]pyridine-7-one (0.54 g, 1.0 mmol), δ-valerolactam (0.12 g, 1.2 mmol), 1,2-diaminocyclohexane (11.4 mg, 0.1 mmol), K3PO4 (0.42 g, 2 mmol) and CuI (2 mg, 0.01 mmol) were added to 5 mL of 1,4-dioxane. The mixture was degassed under argon and stirred at 110° C. under N2 for 48 h. The mixture was then cooled to rt. The dioxane was removed. The residue was dissolved in EtOAc (100 mL), washed with HCl (1N, 30 mL), water (50 mL×2), and brine (50 mL), dried over Na2SO4, filtered, and concentrated. The residue was purified via flash chromatography on silica gel using 1:2 hexane:ethylacetate to give the desired product (0.41 g, 80% yield). LRMS (ES+): 507.1 (M+H)+. 1H NMR (CDCl3) δ 7.68–7.65 (m, 1H), 7.50–7.45 (m, 1H), 7.36–7.16 (m, 5H), 4.16 (t, 2H), 3.64–3.62 (m, 2H), 3.47 (br, 3H), 3.17 (t, 2H), 2.62 (t, 2H), 1.98–1.96 (m, 3H).
