Hydrazine hydrate (1:1) → 5-[2-(4-Chlorophenyl)-ethyl]-1H-pyrazole-3-carboxylic acid ethyl ester

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Reaction Steps

Hydrazine hydrate (0.300 mL, 6.18 mmol) was added to a stirring room temperature solution of 67 (0.1.7484 g, 6.18 mmol) in EtOH (6.2 mL, 1 M) under N2. The reaction was then heated to reflux until judged complete by HPLC (40 min): Upon cooling, a white crystalline solid precipitated from the reaction. The solid was separated by filtration, washed with EtOH, and dried to obtain pure 68 (0.9092 g, 52.7%): 1H (CDCl3, 300 MHz): δ 12.44 (1H, broad s), 7.21 (2H, d, J=8.3 Hz), 7.08 (2H, d, J=8.1 Hz), 6.58 (1H, s), 4.33 (2H, q, J=7.0 Hz), 3.00 (2H, t, J=7.0 Hz), 2.93 (2H, t, J=7.0 Hz), 1.33 (3H, t, J=7.0 Hz) ppm. Partial 13C (CDCl3, 75 MHz): δ 139.12, 131.93, 129.67, 128.50, 106.49, 60.94, 34.72, 14.20 ppm. HPLC: 10.269 min.

Provenance & Evidence