2-Bromo-4-phenylpyridine → (S)-2-(tert-butoxy)-2-(7-(4,4-dimethylpiperidin-1-yl)-5-methyl-2-(4-phenylpyridin-2-yl)pyrazolo[1,5-a]pyrimidin-6-yl)acetic acid

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To a solution of (S)-methyl 2-(2-bromo-7-(4,4-dimethylpiperidin-1-yl)-5-methylpyrazolo[1,5-a]pyrimidin-6-yl)-2-(tert-butoxy)acetate (0.050 g, 0.107 mmol, 1 equiv) in dioxane (1.0 mL) was added 2-bromo-4-phenylpyridine (0.030 g, 0.128 mmol, 1.2 equiv), hexabutyldistannane (0.12 mL, 0.235 mmol, 2.2 equiv), and Pd(PPh3)4 (0.012 g, 0.011 mmol, 0.1 equiv). The reaction was heated at 85° C. for 72 h. The reaction temperature was then lowered to 60° C. Methanol (1 mL), water (0.3 mL), and LiOH.H2O (26 mg, 1.07 mmol, 10 equiv) added and heating was continued for 2 h. Upon completion of the saponification, the reaction was removed from heat and filtered through a syringe filter. The crude reaction mixture was purified via preparative LC/MS with the following conditions: Column: Waters XBridge C18, 19×200 mm, 5-μm particles; Guard Column. Waters XBridge C18, 19×10 mm, 5-μm particles; Mobile Phase A: water with 20-mM ammonium acetate; Mobile Phase B: 95:5 acetonitrile:water with 20-mM ammonium acetate; Gradient: 45-85% B over 20 minutes, then a 5-minute hold at 100% B; Flow: 20 mL/min, to provide (S)-2-(tert-butoxy)-2-(7-(4,4-dimethylpiperidin-1-yl)-5-methyl-2-(4-phenylpyridin-2-yl)pyrazolo[1,5-a]pyrimidin-6-yl)acetic acid (3.5 mg, 6%). 1H NMR (500 MHz, DMSO-d6) δ 8.73 (d, J=4.9 Hz, 1H), 8.48 (s, 1H), 7.83 (d, J=7.6 Hz, 2H), 7.75 (d, J=4.0 Hz, 1H), 7.60-7.49 (m, 3H), 7.06 (s, 1H), 5.72 (br. s., 1H), 3.61-3.55 (m, 4H), 2.53 (s, 3H), 1.65 (br. s., 2H), 1.50 (br. s., 2H), 1.18 (s, 9H), 1.11 (br. s., 6H). LCMS (ESI, M+1): 528.3.

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