[H-].[Na+].[CH2:3]([O:10][C:11]1[CH:20]=[C:14]2[C:15](=[O:19])[NH:16][CH2:17][CH2:18][N:13]2[N:12]=1)[C:4]1[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=1.Br[CH2:22][CH:23]1[CH2:25][CH2:24]1>CN(C=O)C.O>[CH2:3]([O:10][C:11]1[CH:20]=[C:14]2[C:15](=[O:19])[N:16]([CH2:22][CH:23]3[CH2:25][CH2:24]3)[CH2:17][CH2:18][N:13]2[N:12]=1)[C:4]1[CH:5]=[CH:6][CH:7]=[CH:8][CH:9]=1
A 60% dispersion of sodium hydride in mineral oils (8.14 mg, 0.2 mmol) was added to a stirred solution of 2-(benzyloxy)-6,7-dihydropyrazolo[1,5-a]pyrazin-4(5H)-one (0.045 g, 0.18 mmol) in DMF (2.7 mL) at 0° C. The mixture was stirred at 0° C. for 15 minutes. Then (bromomethyl)cyclopropane (22 μL, 0.22 mmol) was added at 0° C. The mixture was stirred at 0° C. for 1 hour and then allowed to warm to room temperature and stirred for 16 hours. The mixture was diluted with water and extracted with AcOEt. The organic layer was separated, washed with a saturated solution of NH4Cl, dried (Na2SO4), filtered and the solvents evaporated in vacuo. The crude product was purified by flash column chromatography (silica; AcOEt in DCM 0/100 to 20/80). The desired fractions were collected, the solvents evaporated in vacuo and the residue was triturated with DIPE to yield 2-(benzyloxy)-5-(cyclopropylmethyl)-6,7-dihydropyrazolo[1,5-a]pyrazin-4(5H)-one (42 mg, 76% yield) as a white solid. C17H19N3O2. 1H NMR (500 MHz, CDCl3) δ ppm 0.25-0.36 (m, 2H), 0.51-0.62 (m, 2H), 0.98-1.08 (m, 1H), 3.43 (d, J=6.9 Hz, 2H), 3.83 (dd, J=6.9, 5.5 Hz, 2H), 4.23 (dd, J=6.9, 5.5 Hz, 2H), 5.20 (s, 2H), 6.26 (s, 1H), 7.29-7.35 (m, 1H), 7.37 (t, J=7.4 Hz, 2H), 7.41-7.48 (m, 2H).
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