[N:1]1[NH:2][CH:3]=[C:4]2[CH2:8][N:7]([C:9]([O:11][C:12]([CH3:15])([CH3:14])[CH3:13])=[O:10])[CH2:6][C:5]=12.[H-].[Na+].[CH3:18][Si:19]([CH3:26])([CH3:25])[CH2:20][CH2:21][O:22][CH2:23]Cl>CN(C=O)C>[CH3:18][Si:19]([CH3:26])([CH3:25])[CH2:20][CH2:21][O:22][CH2:23][N:2]1[CH:3]=[C:4]2[CH2:8][N:7]([C:9]([O:11][C:12]([CH3:15])([CH3:14])[CH3:13])=[O:10])[CH2:6][C:5]2=[N:1]1To a stirred solution of tert-butyl 2,6-dihydropyrrolo[3,4-c]pyrazole-5(4H)-carboxylate (20 g, 96 mmol) in DMF (200 mL) at 0° C. was added sodium hydride (4.21 g, 105 mmol). After stirring for 1 h at RT, 2-trimethylsilylethoxymethyl chloride (SEM-Cl) (4.65 mL, 26.3 mmol) was added. The resulting mixture was stirred at RT overnight. The mixture was quenched with saturated NH4OH, and the solvents were removed. The residue was diluted with ethyl acetate (500 mL), washed with water, brine, dried over anhydrous sodium sulfate and concentrated. The residue was purified by column chromatography on a silica gel Biotage 65i® column, eluting with 0 to 20% ethyl acetate in hexanes to give the title compound as a colorless gum. LC-MS: 340.1 (M+H)
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