518990-21-1, These common heterocyclic compound, 518990-21-1, name is Ethyl 1,4,6,7-tetrahydropyrano[4,3-c]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.
The crude 1,4,6,7-tetrahydropyrano[4,3-c]pyrazole-3-carboxylic acid ethyl ester (3) (915 g) was dissolved in ethanol (1.8 L).An aqueous solution (3.6 L) of lithium hydroxide (424 g, 11 mol, 2.2 eq.) was slowly added dropwise at a temperature of 10-20 C.After the completion of the dropwise addition, the temperature was raised to 50 C, and the reaction was carried out for 2-3 h. The reaction was confirmed by TLC.After concentrating the reaction mixture, the pH was adjusted to 1-2 with dilute hydrochloric acid at 10-20 C, and a white solid precipitated.Stir for 30 min, filter, wash with water (900 mL * 2), dry,A white powder of 547 g was obtained in a yield of 65% and a UPLC purity of 99%.
Chemical properties determine the actual use. Each compound has specific chemical properties and uses. We look forward to more synthetic routes in the future to expand reaction routes of 518990-21-1.