6-NITRO-4-INDAZOLECARBOXYLIC ACID METHYL ESTER synthesis

Yield:-

Reaction Conditions:

with acetic acid;sodium nitrite in water at 20;Cooling with ice;

Steps:

41.1

First Step [Show Image] To a glacial acetic acid solution (450 mL) of methyl 3-amino-2-methyl-5-nitrobenzoate [which can be synthesized, for example, by the method described in JP04295441] (3.99 g, 19.0 mmol), an aqueous solution (8 mL) of sodium nitrite (1.35 g, 19.6 mmol) was added under ice cooling. After stirring under ice cooling for one hour, the solution was further stirred at room temperature for 3 days. Acetic acid was distilled off under reduced pressure and water was added to the resulting residue, followed by stirring under ice cooling for 30 minutes. The precipitate was collected by filtration to obtain 3.99 g of methyl 6-nitro-1H-indazole-4-carboxylate. ¹H-NMR (-NMR (500 MHz, DMSO-d₆) d: 4.02 (s, 3H), 8.48 (d, 1H, J = 1.6 Hz), 8.62 (d, 1H, J = 0.8 Hz), 8.76 (br, 1H).

References:

EP2226315,2010,A1 Location in patent:Page/Page column 44-45