Hydrochloric Acid → 4-(2,2,2-Trifluoro-ethoxy)-1H-pyrazole-3,5-dicarboxylic acid diethyl ester

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Reaction Steps

To a solution of 1 g 4-Iodo-1H-pyrazole-3,5-dicarboxylic acid diethyl ester in 5 ml 2,2,2-trifluoro-ethanol 1.4 g Cs2CO3, 56 mg CuI and 106 mg 1,10-Phenanthroline were added. The reaction mixture heated for 4 h to 100° C. under microwave irradiation (100 W, CEM Discover™ apparatus). Then 10 HCl in ethanol (8M) was added and the solution was stirred at RT. After 16 h the solvents were removed under reduced pressure and the residue taken up in DCM and water. The organic phase was separated and the aqueous layer was extracted with DCM (2×50 ml). The combined organic layers were dried over MgSO4, filtered and the solvent was removed under reduced pressure. The residue was purified by preparative HPLC (C18 reverse phase column, elution with a H2O/MeCN gradient with 0.1% TFA). The fractions containing the product were evaporated and lyophilized to yield a white solid. Yield: 359 mg.

Provenance & Evidence