1-(cyclopropylmethyl)-1H-pyrazol-3-amine synthesis

Yield: 95%

Reaction Conditions:

with hydrazine;nickel in methanol;water;ethyl acetate for 0.5 h;

Steps:

69
The 1-cyclopropylmethyl-3-nitro-1H-pyrazole (217 mg, 1.30 mmol) was dissolved in methanol (6 mL) and ethyl acetate (6 mL) was added. While stirring, a 50% slurry of raney nickel in water (1.5 mL) was added followed by hydrazine (250 μL). Immediate effervescence was observed. The reaction continued to stir and bubble for 30 min. The reaction was passed through a plug of celite and concentrated in vacuo to give an oil. The oil was taken up in ethyl acetate (40 mL), washed with water (2×10 mL), saturated aqueous brine solution (10 mL), dried over magnesium sulfate and concentrated in vacuo to give the desired product, 1-cyclopropylmethyl-1H-pyrazol-3-ylamine (169 mg, 95%) as a waxy beige solid: H¹-NMR (400 MHz, CDCl₃) δ 0.02 (2H, qt, J=5.6 Hz), 0.31 (2H, qt, J=6.8 Hz), 0.88-0.98 (1H, m), 3.20-3.32 (2H, bs), 3.47 (2H, d, J=7.2 Hz), 5.27 (1H, d, J=2.4 Hz), 6.91 (1H, d, J=2.4 Hz).

References:

Berthel, Steven Joseph;Kester, Robert Francis;Murphy, Douglas Eric;Prins, Thomas Jay;Ruebsam, Frank;Sarabu, Ramakanth;Tran, Chinh Viet;Vourloumis, Dionisios US2008/21032, 2008, A1 Location in patent:Page/Page column 63-64