Triethylamine → (2S)-1-[1-(4-fluorophenyl)-6,7-dihydro-5H-pyrazolo[4,3-b]pyridin-4-yl]-2-[2-methyl-4-(trifluoromethyl)imidazol-1-yl]propan-1-one

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Reaction Steps

To a solution of (2S)-2-[2-methyl-4-(trifluoromethyl)imidazole-1-yl]propanoic acid (0.020 g, 0.09 mmol) in CH2Cl2 (3 mL) was added oxalyl chloride (0.040 mL, 0.46 mmol) and DMF (1 drop). After 20 min at room temperature, the mixture was concentrated in vacuo and the residue was added to another flask containing 1-(4-fluorophenyl)-4,5,6,7-tetrahydropyrazolo[4,3-b]pyridine (0.028 g, 0.13 mmol) and NEt3 (0.060 mL, 0.43 mmol) in CH2Cl2 (3 mL). The resulting mixture was stirred at room temperature for 20 min, quenched with saturated aqueous NaHCO3 solution (30 mL), and extracted with ethyl acetate (50 mL). The organic layer was dried over anhydrous sodium sulfate, concentrated in vacuo, and purified by flash chromatography (SiO2, 0-8% MeOH/EtOAc) to afford the titled compound (0.030 g, 44%, TFA salt) as a white solid. 1H NMR (TFA salt) (400 MHz, CDCl3) δ 9.70 (s, 1H), 8.43 (s, 1H), 7.78 (d, J=0.8 Hz, 1H), 7.42 (dd, J=9.2, 8.8 Hz, 2H), 7.20 (dd, J=8.8, 8.4 Hz, 2H), 5.61 (q, J=7.2 Hz, 1H), 3.89 (m, 2H), 2.84 (dd, J=6.2, 6.2 Hz, 2H), 2.65 (s, 3H), 2.15 (m, 2H), 1.84 (d, J=7.2 Hz, 3H); MS: (ES) m/z calculated for C20H19F4N5O [M+H]+ (free form) 422.1, found 422.1; The titled compounds were analyzed by chiral normal phase chromatography (RegisPack, 25 cm×4.6 mm, 5 micron, cat#793104, 0.1% DEA/IPA, 0.7 mL/min). The (S)-enantiomer (major) had a retention time of 7.2 min and the (R)-enantiomer (minor) had a retention time of 6.2 min (isolated in 19:1 er).

Provenance & Evidence