Reaction Steps
To a suspension of sodium hydride, 60% disp. in mineral oil (3:2, sodium hydride: mineral oil, 1.0 g, 25 mmol) in 1,4-dioxane (50 mL, 600 mmol) was added 3-bromo-pyridin-2-ylamine (2.68 g, 15.5 mmol). The mixture was stirred for 5 minutes at room temperature under an atmosphere of nitrogen. 1-Isothiocyanato-4-methoxy-benzene (2.35 mL, 17.0 mmol) was slowly added to the suspension. Slow gas evolution was noted and the suspension slowly thickened to a slurry. The mixture was stirred at room temperature for 18 hours and the volatiles were evaporated to a yield a tan solid. To the solid was added saturated aqueous ammonium chloride solution (100 mL). Gas evolution and exotherm noted. The mixture was stirred for 30 minutes and the waxy solid was filtered. The solid was triturated with ether (50 mL), filtered and rinsed with ether. 1-(3-Bromo-pyridin-2-yl)-3-(4-methoxy-phenyl)-thiourea was isolated as a yellow solid (4.96 g, 95%). 1H NMR (400 MHz, (D3C)2SO, δ, ppm): 12.85 (s, 1H), 8.75 (s, 1H), 8.38 (dd, J=4.8, 1.2 HZ, 1H), 8.24 (dd, J=7.9, 1.3 Hz, 1H), 7.56-7.50 (m, 2H), 7.15 (dd, J=7.9, 4.9 Hz, 1H), 7.00-6.95 (m, 2H), 3.77 (s, 3H). MS=338, 340 (MH)+. 19b) To a suspension of 1-(3-Bromo-pyridin-2-yl)-3-(4-methoxy-phenyl)-thiourea (9.37 g, 27.7 mmol) in 1,4-dioxane (180 mL) was added dimethyl sulfate (2.60 mL, 27.5 mmol). The mixture was stirred at room temperature for 18 hours then heated at 60° C. for 18 hours to complete reaction. The mixture was cooled to room temperature and the volatiles were evaporated. To residue was added saturated aqueous sodium carbonate and shaken. The resulting precipitate was filtered, rinsed with water, dissolved in dichloromethane, dried over magnesium sulfate, filtered and evaporated to a red viscous oil (9.44 g) and was taken on to the next step without purification. 19c) To a solution of the red oil in 1,4-dioxane (100 mL) was added potassium carbonate (20.0 g, 145 mmol) followed by hydroxylamine hydrochloride (9.6 g, 140 mmol). The suspension was heated at 90° C. for 4 days. The mixture was cooled to room temperature and filtered through a plug of diatomaceous earth, the volatiles were evaporated and to the residue was added water (200 mL). The mixture was extracted with ethyl acetate (200 mL), washed with water (2×100 mL), dried over magnesium sulfate, filtered and evaporated to an orange waxy solid (8.81 g) and taken on to the next step without further purification. 19d) To a suspension of the orange waxy solid and potassium carbonate (3.0 g) in acetonitrile (100 mL, 2000 mmol) was added by slow addition 20% phosgene in toluene (1:4, phosgene:toluene, 22 mL, 42 mmol). The mixture was stirred for 36 hours. The suspension was filtered through a plug of diatomaceous earth and the filtrate was evaporated to a resin. To the residue was added water (100 mL) and extracted with dichloromethane (2×100 mL). The organic layer was dried over magnesium sulfate, filtered and evaporated. The residue was purified via chromatography utilizing an ISCO automated purification apparatus with an amine modified silica gel column (140 g) with ethyl acetate:hexane solvent gradient. (8-Bromo-[1,2,4]triazolo[1,5-a]pyridin-2-yl)-(4-methoxy-phenyl)-amine was isolated as a tan solid (5.2 g, 58%). 1H NMR (400 MHz, (D3C)2SO, δ, ppm): 9.67 (s, 1H), 8.79 (dd, J=6.7, 0.9 Hz, 1H), 7.86 (dd, J=7.7, 0.9 Hz, 1H), 7.60-7.55 (m, 2H), 6.94-6.88 (m, 3H), 3.72 (s, 3H). MS=319, 321 (MH)+. 19e) The title compound, [8-(4-Methanesulfonyl-phenyl)-[1,2,4]triazolo[1,5-a]pyridin-2-yl]-(4-methoxy-phenyl)-amine, was prepared from (8-bromo-[1,2,4]triazolo[1,5-a]pyridin-2-yl)-(4-methoxy-phenyl)-amine (253.0 mg, 0.7927 mmol) and (4-methylsulfonylphenyl)boronic acid (175.0 mg, 0.8749 mmol) with Pd(dppf)Cl2 (0.058 g) as the catalyst in a manner analogous to Step 2c and was isolated as a yellow solid (0.21 g, 67%). MP=208-212° C. 1H NMR (400 MHz, CDCl3, δ, ppm): 8.47 (d, J=6.6 Hz, 1H), 8.23 (d, J=8.5 Hz, 2H), 8.09 (d, J=8.5 Hz, 2H), 7.64 (d, J=7.4 Hz, 1H), 7.00 (dd, J=6.8, 6.8 Hz, 1H), 6.95-6.90 (m, 2H), 6.71 (s, 1H), 3.82 (s, 3H), 3.10 (s, 3H). MS=395 (MH)+.
