Reaction Steps
N-Bromosuccinimide (13.5 g, 76.0 mmol) was added in portions over 1.5 h to a stirred solution of methyl 2-amino-5-iodobenzoate (20 g, 72 mmol) in CHCl3 (320 mL) at RT. This was stirred overnight and then silica gel chromatography (step gradient elution with hexane containing 10 to 30% DCM) afforded impure methyl 2-amino-3-bromo-5-iodobenzoate (21 g) as a white solid that was used as such. A flask containing a mixture of 3- (trifluoromethyl)phenylboronic acid (3.73 g, 19 6 mmol), methyl 2-amino-3-bromo-5-iodobenzoate (7.0 g, 16 mmol), K2CO3 (6.85 g, 49 6 mmol), 1,1′-bis(diphenylphosphino)ferrocene-palladium(II)dichloride dichloromethane complex (1.4 g, 1 7 mmol), dioxane (140 mL), and water (28 mL) was degassed and flushed with N2 twice and then heated at 70° C. for 3 h. It was cooled to RT, diluted with EtOAc, washed with water (2×), brine, and then dried over Na2SO4. Removal of the solvents followed by silica gel chromatography (step gradient elution with DCM containing 0 to 7% MeOH) afforded impure methyl 4-amino-5-bromo-3′-(trifluoromethyl)biphenyl-3-carboxylate (6.2 g, 10.44 mmol, 63.2% yield) as a white solid that was used as such. A mixture of 1-methyl-4-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)piperazine (303 mg, 1.00 mmol), methyl 4-amino-5-bromo-3′-(trifluoromethyl)biphenyl-3-carboxylate (250 mg, 0.668 mmol), tetrakistriphenylphosphine palladium(0) (77 mg, 0.067 mmol), K2CO3 (369 mg, 2.67 mmol) in a microwave vial was flushed with nitrogen and DMF (2.7 mL) was added. The vial was sealed and heated at 100° C. overnight. The reaction was partitioned between EtOAc and water. The organic phase was washed with brine, dried over sodium sulfate, and the solvent removed. Silica gel chromatography (step gradient elution with hexane containing 0, to 20% EtOAc) afforded methyl 4′-amino-4″-(4-methylpiperidin-1-yl)-3-trifluoromethyl-[1,1′:3′,1″-terphenyl]-5′-carboxylate (150 mg, 0.532 mmol, 80% yield). MS (ESI) m/z 470.20 (M+H). 1H NMR (500 MHz, chloroform-d) δ ppm 8.16 (1H, d, J=2.14 Hz), 7.81 (1H, s), 7.73-7.78 (1H, m), 7.49-7.56 (3H, m), 7.37 (2H, d, J=8.55 Hz), 7.05 (2H, d, J=8.55 Hz), 6.15 (2H, br, s.), 3.95 (3H, s), 3.26-3.38 (4H, m), 2.60-2.69 (4H, m), 2.39 (3H, s).
