Hydrazine hydrate (1:1) → 5-(4-methylpentyl)-1H-pyrazole-3-carboxylic acid ethyl ester

Participants

Reaction Steps

Hydrazine hydrate (0.943 mL, 1.91 mmol) was added to a stirring room temperature solution of 16 (0.4354 g, 1.91 mmol) in EtOH (1.9 mL, 1 M) under N2. The reaction was then heated to reflux until judged complete by TLC. 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 0.3132 g (63.1%) of 17. 1H (CDCl3, 400 MHz): δ 9.60 (1H, broad s), 6.58 (1H, s), 4.34 (2H, q, J=7.2 Hz), 2.66 (2H, t, J=7.7 Hz), 1.67-1.57 (2H, m), 1.58 (1H, m), 1.36 (3H, t, J=7.2 Hz), 1.24-1.15 (2H, m), 0.85 (6H, d, J=6.5 Hz) ppm. Partial 13C (CDCl3, 100 MHz): δ 162.22, 106.59, 61.17, 38.58, 27.99, 27.20, 26.57, 22.72, 14.48 ppm. DEPT (CDCl3, 100 MHz): CH3 carbons: 22.72, 14.48; CH2 carbons: 61.17, 38.58, 27.20, 26.57; CH carbons: 106.59, 27.99 ppm. HPLC: 10.072 min.

Provenance & Evidence