Reaction Steps
To a solution of 5-(methoxycarbonyl)pyridine-2-carboxylic acid (0.209 g, 1.18 mmol, 1.0 eq) and 1-(4-methoxybenzyl)piperidine dihydrochloride (0.373 g, 1.27 mmol, 1.1 eq) in dimethylformamide (10 mL) was added triethylamine (0.40 mL, 2.89 mmol, 2.5 eq) followed by HATU (0.528 g, 1.39 mmol, 1.2 eq). The reaction was stirred at room temperature for 2 days before partitioning between EtOAc (100 mL) and water (80 mL). The organics were further washed with brine (80 mL), water (80 mL) and brine (80 mL), before drying (Na2SO4) and concentrating under reduced pressure to yield methyl 6-(1-(4-methoxybenzyl)piperidin-4-ylcarbamoyl)nicotinate as a white solid (0.378 g, 84%) which was used without further purification; 1H nmr (CDCl3) 9.13 (1H, m, pyH-6), 8.43 (1H, dd, J 8.0, 2.0 Hz, pyH-4), 8.25 (1H, d, J 8.0 Hz, pyH-3), 7.98 (1H, d, J 7.5 Hz, NH), 7.26 (2H, d, J 8.5 Hz, 2H of C6H4OCH3), 6.87 (2H, d, J 8.5 Hz, 2H of C6H4OCH3), 4.01 (1H, m, pipH-4), 3.98 (3H, s, 1×OCH3), 3.80 (3H, s, 1×OCH3), 3.53 (2H, s, CH2C6H4OCH3), 2.90 (2H, m, 2H of pip), 2.24 (2H, dd, J 11.0, 10.0 Hz, 2H of pip), 2.02 (2H, m, 2H of pip), 1.69 (2H, m, 2H of pip); m/z 384 [M+H]+. To a solution of the methyl 6-(1-(4-methoxybenzyl)piperidin-4-ylcarbamoyl)nicotinate (0.378 g, 0.987 mmol, 1.0 eq) in tetrahydrofuran (6 mL) and methanol (3 mL) was added a solution of lithium hydroxide monohydrate (0.166 g, 3.948 mmol, 4.0 eq) in water (3 mL). The reaction mixture was stirred at room temperature for 30 minutes before neutralizing with HCl (approximately 2.0 mL of a 2M solution). The reaction was concentrated to dryness to yield 6-(1-(4-methoxybenzyl)piperidin-4-ylcarbamoyl)nicotinic acid as a white solid, which was used without purification. To a mixture of the 6-(1-(4-methoxybenzyl)piperidin-4-ylcarbamoyl)nicotinic acid (0.036 g, 0.098 mmol, 1.0 eq), 4-fluorobenzoylpiperidine hydrochloride (0.029 g, 0.117 mmol, 1.2 eq), and triethylamine (0.034 mL, 0.244 mmol, 2.5 eq) in dimethylformamide (1.0 eq) was added HATU (0.041 g, 0.244 mmol, 1.1 eq). The reaction was shaken at room temperature for 3 hours before adding water (5 mL). A gum formed, which was dissolved in EtOAc—CH2Cl2 (4:1, 50 mL). The solution was washed with NaHCO3-water (1:1, 50 mL), brine (50 mL), water (50 mL) and brine (50 mL). The organics were dried (Na2SO4) and concentrated under reduced pressure. Column chromatography (silica, 3→7% MeOH—CH2Cl2) yielded Compound 160 as a colourless oil (0.037 g, 68%); 1H nmr (CDCl3) δ 8.60 (1H, m, pyH-6), 8.24 (1H, d, J 8.0 Hz, pyH-3), 7.98 (2H, dd, J 8.5, 5.5 Hz, 2H of C6H4F), 7.91 (1H, m, NH), 7.88 (1H, dd, J 8.0, 2.0 Hz, pyH-4), 7.24 (2H, d, 2H of C6H4OCH3), 7.16 (2H, t, J 8.5 Hz, 2H of C6H4F), 6.86 (2H, d, J 8.5 Hz, 2H of C6H4OCH3), 4.66 (1H, m, BzpipH-4), 3.99 (1H, m, pipH-4), 3.80 (3H, s, OCH3), 3.77 (1H, m, 1H of BzpipH-2, H-6), 3.54 (1H, m, 1H of BzpipH-2, H-6), 3.48 (2H, s, CH2C6H4OCH3), 3.21-3.11 (2H, m, 2H of BzpipH-2, H-6), 2.86 (2H, m, 2H of pipH-2, H-6), 2.19 (2H, t, J 11.0 Hz, 2H of pipH-2, H-6), 2.00 (2H, m, 2H of pipH-3, H-5), 1.82 (4H, m, BzpipH-3, H-5), 1.64 (2H, m, 2H of pipH-3, H-5); m/z: 559 [M+H]+.
