Cl.[CH3:2][C:3]1[CH:8]=[CH:7][CH:6]=[CH:5][C:4]=1[NH:9][NH2:10].[CH:11]1([C:16](=O)[CH2:17][C:18]#[N:19])[CH2:15][CH2:14][CH2:13][CH2:12]1>C1(C)C=CC=CC=1>[CH:11]1([C:16]2[CH:17]=[C:18]([NH2:19])[N:9]([C:4]3[CH:5]=[CH:6][CH:7]=[CH:8][C:3]=3[CH3:2])[N:10]=2)[CH2:15][CH2:14][CH2:13][CH2:12]1A solution of (2-methylphenyl)hydrazine hydrochloride (2.00 g, 14.6 mmol) and crude 3-cyclopentyl-3-oxopropanenitrile from the previous step (2.32 g, ˜14.6 mmol) in toluene (6 mL) was heated to reflux for 16 h. Removal of the solvent under reduced pressure provided a residue which was purified by silica gel chromatography using hexane/EtOAc (3:1, v/v) as the eluent. Concentration under reduced pressure provided 3-cyclopentyl-1-(2-methylphenyl)-1H-pyrazol-5-amine as a light orange solid (2.19 g, 62%). ES-MS m/z 241.9 (MH+); HPLC RT (min) 1.69. 1H NMR (400 MHz, CDCl3) δ 1.58-1.82 (m, 6H), 2.00-2.16 (m, 2H), 2.17-2.21 (s, 3H), 2.93-3.11 (m, 1H), 3.42-3.58 (s, 2H), 5.41-5.46 (s, 1H), 7.20-7.28 (m, 2H) 7.29-7.37 (m, 2H).
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