[NH2:1][C:2]1[CH:6]=[CH:5][NH:4][N:3]=1.[Cl:7][CH2:8][CH2:9][CH2:10][N:11]=[C:12]=[O:13].[N-]=[C:15]=O.[CH2:17]([Cl:19])Cl.[CH3:20][N:21]([CH:23]=[O:24])C>>[Cl:7][CH2:8][CH2:9][CH2:10][NH:11][C:12]([N:4]1[CH:5]=[CH:6][C:2]([NH:1][C:23]([NH:21][CH2:20][CH2:15][CH2:17][Cl:19])=[O:24])=[N:3]1)=[O:13]To a solution of 3-aminopyrazole (500 mg, 6 mmol), in anh. DMF (10 mL), at r.t., under N2, was added 3-chloropropyl isocyanate (1.2 mL, 2 eq) and the reaction was stirred for 24 hr. The reaction was not complete and more isocyanate (1.2 mL, 2 eq) was added. The reaction mixture was stirred for an additional 48 hr. It was then poured into CH2Cl2/sat.aq. NaCl and the phases were separated. The aqueous layer was extracted with CH2Cl2 (2×20 mL) and the combined organic extracts were dried over anh. Na2SO4. The solids were filtered and the solvent evaporated. The crude product was purified by flash chromatography (Biotage 40, cHex/EtOAc 7:3) to give the title compound as a white solid (620 mg, 32%).
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