Hydrazine hydrate (1:1) → 5-(3-methylbutyl)-1H-pyrazole-3-carboxylic Acid Ethyl Ester

Participants

Reaction Steps

Hydrazine hydrate (1.43 mL, 2.95 mmol) was added to a stirring room temperature solution of 46 (6.3112 g, 2.95 mmol) in EtOH (29.5 mL, 1 M) under N2. The reaction was then stirred at room temperature until judged complete by HPLC (35 min): The reaction was concentrated and purified by silica gel chromatography (Combiflash column, 96:4 Hexanes:2N NH3 in EtOH): Only pure fractions were combined and concentrated to obtain 4.3911 g (70.9%) of 47. 1H (CDCl3, 400 MHz): δ 13.01 (1H, broad s), 6.52 (1H, s), 4.29 (2H, q, J=7.1 Hz), 2.64 (2H, t, J=7.8 Hz), 1.57-1.41 (3H, m), 1.26 (3H, t, J=7.1 Hz), 5.85 (6H, d, J=5.9 Hz) ppm. 13C (CDCl3, 100 MHz): δ 162.37, 146.26, 143.1, 105.73, 60.53, 37.88, 27.35, 23.42, 22.11, 14.06 ppm. HPLC: 10.006 min.

Provenance & Evidence