m-Chlorophenylhydrazine hydrochloride → 1-(3-chlorophenyl)-3-methyl-1H-pyrazol-5-amine

Participants

Reaction Steps

(see, e.g., Ganesan, A., et al., Journal of Organic Chemistry 1993, 58, 6155-6157). A solution of 3-aminocrotonitrile (mixture of cis and trans) (1.50 g, 17.5 mmol) and 3-chlorophenylhydrazine hydrochloride (3.0 g, 16.2 mmol) in 25 mL of 1N HCl was heated to reflux for 3 h under nitrogen. The reaction mixture was diluted with H2O (30 mL) and extracted with EtOAc (20 mL×2). The combined organic layers were washed with brine, dried (Na2SO4), filtered, and concentrated under reduced pressure. The crude was recrystallized from hot iPrOH to give the title compound (677 mg, 20%) as a beige fluffy solid. 1H NMR (500 MHz, CDCl3) δ 7.62 (s, 1H), 7.48 (d, J=8.0 Hz, 1H), 7.37 (t, J=8.0 Hz, 1H), 7.28 (d, J=9.5 Hz, 1H), 5.46 (s, 1H), 2.22 (s, 3H). 13C NMR (125 MHz, CDCl3) δ 149.95, 145.30, 139.87, 135.05, 130.32, 126.86, 123.67, 121.28, 91.41, 13.89.

Provenance & Evidence