These common heterocyclic compound, 5932-27-4, name is Ethyl 1H-pyrazole-3-carboxylate, its traditional synthetic route has been very mature, but the traditional synthetic route has various shortcomings, such as complicated route, low yield, poor purity, etc, below Introduce a new synthetic route. 5932-27-4
(b) 4-Fluoropyrazole-3-carboxylic acidSodium hydroxide (aq., 2M, 18 mmol; 9 mL) was added to a solution of a mixture (-2:1) of 4-fluoropyrazole-3-carboxylic acid ethyl ester and pyrazole-3-carboxylic acid ethyl ester (1.2 g, ~8 mmol; see step (a) above) in dioxane (9 mL) at rt and was stirred for 16 h. A second portion of aqueous sodium hydroxide (2M, 18 mmol, 9 mL) was added and the mixture was stirred for another 4 h. The mixture was acidified with HCl (aq., 2M, 20 mL), concentrated, stirred with MeOH (30 mL) and filtered. The filtrate was concentrated and the residue crystallised from HCl (aq., 0.01M)