Hydrochloric Acid → Methyl 1-benzyl-3-methyl-1H-pyrazole-5-carboxylate

関与物質

反応手順

To a stirring solution of 21.91 g (13.63 mmol) of 5-methyl-2H-pyrazole-3-carboxylic acid methyl ester, prepared as in Part A, in 50 mL of DMF is added 2.88 g (20.44 mmol, 1.5 equiv) of K2CO3, followed by 1.95 mL (16.35 mmol, 1.2 equiv) of benzyl bromide. The reaction mixture is stirred 15 min at RT then heated at 50° C. for 20 h. The reaction is cooled to RT, poured into 100 mL 1N HCl, and extracted with Et2O (2×100 mL). The organic layers were washed with H2O (2×100 mL), dried (MgSO4), and the solvent removed in vacuo. Purification of the crude material by silica gel flash column chromatography using a gradient elution of hexane/EtOAc 10/1 to 1/1 afforded 833 mg of 2-Benzyl-5-methyl-2H-pyrazole-3-carboxylic acid methyl ester as a yellow oil: 1H NMR (CDCl3, 300 MHz) δ7.42-7.25 (m, 5H), 6.68 (s, 21H), 5.74 (s, 2H), 3.86 (s, 3H), 2.34 (s, 3H).

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