[F:1][C:2]([F:15])([F:14])[CH2:3][NH:4][C:5]([N:7]1[CH2:11][CH:10]([CH2:12][CH3:13])[CH:9]=[N:8]1)=[S:6].I[CH3:17]>CO>[CH3:17][S:6][C:5]([N:7]1[CH2:11][CH:10]([CH2:12][CH3:13])[CH:9]=[N:8]1)=[N:4][CH2:3][C:2]([F:1])([F:14])[F:15]2.80 g (1 mol equiv.) 4-Ethyl-4,5-dihydro-pyrazole-1-carbothioic acid (2,2,2-trifluoro-ethyl)-amide was dissolved in 56 mL methanol; 7.3 mL (10 mol equiv.) iodomethane was added and the reaction mixture was heated at 50° C. for 4 hours. Volatiles were removed under reduced pressure, and the residue was taken up in DCM and extracted with 5% aqueous NaHCO3. The organic layer was washed twice with water, dried over Na2SO4, filtered and evaporated to dryness. Purification by flash chromatography on silica gel (Et2O:PA=1:1) afforded 0.57 g (19%) 4-ethyl-N-(2,2,2-trifluoro-ethyl)-4,5-dihydro-pyrazole-1-carboximidothioic acid methyl ester. 1H NMR (400 MHz, CDCl3) δ 0.99 (t, J=7.5 Hz, 3H), 1.46-1.70 (m, 2H), 2.48 (s, 3H), 3.01-3.11 (m, 1H), 3.50 (dd, J=11.5, 7.8 Hz, 1H), 3.90 (t, J=11.5 Hz, 1H), 3.99-4.11 (m, 2H), 6.85 (d, J=1.5 Hz, 1H).
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