Collect. Czech. Chem. Commun. 1989, 54, 196-199

Photochemical synthesis of 4-ethoxycarbonyl-5-hydroxypyrazoles

Maria K. Spassova and Rossitza D. Zakharieva

Institute of Molecular Biology, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria


The photochemical decomposition of 4-ethoxycarbonyl-5-diazopyrazoles in tetrafluoroboric acid results in corresponding 4-ethoxycarbonyl-5-hydroxypyrazoles (V-VII). The irradiation of the diazocompound in dioxane, toluene or tetrahydrofurane proceeds with a reductive decomposition producing corresponding 4-ethoxycarbonylpyrazole (VIII) as the main photoproduct.