CCN(/[CH:6]=[C:7](/[C:11]([O:13][CH2:14][CH3:15])=[O:12])\[C:8]([CH3:10])=O)CC.Cl.[C:17]([NH:21][NH2:22])([CH3:20])([CH3:19])[CH3:18]>CCO>[C:17]([N:21]1[C:8]([CH3:10])=[C:7]([C:11]([O:13][CH2:14][CH3:15])=[O:12])[CH:6]=[N:22]1)([CH3:20])([CH3:19])[CH3:18]A stirred solution of diethylaminomethylene ethyl acetoacetate (552 mg, 2.8 mmol, see R. A. Fecik, P. Devasthale, S. Pillai, A. Keschavarz-Shokri, L. Sehn, and L. A. Mitscher; J. Med. Chem. 2005, 48, 1229) and tert-butyl hydrazine hydrochloride (387 mg, 3.1 mmol) in EtOH (5 mL) was heated to reflux for 15 h. The reaction mixture was cooled to room temperature and concentrated under reduced pressure. The residue was dissolved in EtOAc and saturated aqueous NaHCO3. The layers were separated and the aqueous layer was extracted with EtOAc (2×10 mL). The combined organic layer was washed with brine, dried with Na2SO4 and concentrated under reduced pressure to provide ethyl 1-tert-butyl-5-methyl-1H-pyrazole-4-carboxylate (560 mg, 96%) as a yellow oil.
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