Cyclopentylamine → 1-[7-(Cyclopentylamino)-2-(4-fluorophenyl)pyrazolo[1,5-a]pyridin-3-yl]ethanone

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To a solution of 1-[7-chloro-2-(4-fluorophenyl)pyrazolo[1,5-a]pyridin-3-yl]ethanone (2.7 g, 9.5 mmol) in toluene (50 mL) was added successively racemic-BINAP (378 mg, 0.6 mmol), cesium carbonate (4.7 g, 14.3 mmol), cyclopentylamine (4.7 mL, 47.5 mmol), and palladium(II) acetate (86 mg, 0.4 mmol). The resultant mixture was heated to 95° C. for 2.5 hours at which time the reaction was judged complete by thin layer chromatography. The solution was cooled to room temperature and ether was added. The organic layer was washed with water and brine. The aqueous layer was extracted with ether and the combined organics dried over magnesium sulfate. Filtration and concentration followed by flash chromatography (4:1 hexanes-ethyl acetate) provided 1-[7-(cyclopentylamino)-2-(4-fluorophenyl)pyrazolo[1,5-a]pyridin-3-yl]ethanone (3.1 g, 95%) as a yellow solid. 1H NMR (CDCl3): δ 7.62 (d, 1 H), 7.55 (dd, 2 H), 7.40 (t, 1 H), 7.15 (t, 2 H), 6.10 (d, 1 H), 5.99 (d, 1 H), 3.94 (m, 1 H), 2.09 (s, 3 H), 2.12-2.04 (m, 2 H), 1.78-1.58 (m, 6 H); 13C NMR (CDCl3) δ 192.63, 163.28 (d, JCF=247.3 Hz), 154.89, 142.65, 142.38, 131.66 (d, JCF=8.3 Hz) 131.09, 130.03 (d, JCF=3.8 Hz), 115.33 (d, JCF=22.0 Hz), 111.32, 105.41, 91.97, 53.81, 33.21, 30.10, 23.96; 19F NMR (CDCl3) δ −112.70; MS m/z 338 (M+1).

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