Yield:55904-61-5 98%

Reaction Conditions:

with hydrogen;palladium 10% on activated carbon in ethanol; for 20 h;

Steps:

3.B

A mixture of 4-nitro-lH-pyrazole-3-carboxylic acid ethyl ester (6.40 g, 34.6 mmol) and 10% Pd/C (650 mg) in EtOH (150ml) was stirred under an atmosphere of hydrogen for 20 h. The mixture was filtered through a plug of Celite, reduced in vacuo and dried through azeotrope with toluene to afford 4-amino-lH-pyrazole-3- carboxylic acid ethyl ester as a pink solid (5.28 g, 98%). (¹H NMR (400 MHz, DMSOd₆) δ 12.7 (s, IH)₅ 7.1 (s, IH), 4.8 (s, 2H)₅ 4.3 (q, 2H), 1.3 (t, 3H)).

References:

WO2006/70198,2006,A1 Location in patent:Page/Page column 123