Methyl acetoacetate → 1-tert-butyl-5-methyl-1H-pyrazole-4-carboxylic acid

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Reaction Steps

The title compound was prepared according to the procedure as described in Anderson, K. W., et al., PCT Publication, WO 2007/107470, published Sep. 27, 2007, as described in Example 54, Steps 2 and 3, pages 97-98, and substituting triethylamine for the sodium acetate reagent in Step 2) from methyl acetoacetate (1.14 mL, 10.6 mmol), DMFDMA (1.48 mL, 11.1 mmol), tert-butylhydrazine hydrochloride (1.32 g, 10.6 mmol), and TEA (4.43 mL, 31.8 mmol) to yield methyl 1-tert-butyl-5-methyl-1H-pyrazole-4-carboxylate after chromatography using a 80-g SiO2 pre-packed column eluting with 0:1-3:7 EtOAc/heptane. Said product was used directly in the next step without further purification. 1H-NMR (400 MHz, CDCl3) δ: 7.78 (s, 1H), 3.80 (s, 3H), 2.75 (s, 3H), 1.66 (s, 9H).

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