Rearrangements and Tautomeric Transformations of Heterocyclic Compounds in Homogeneous Reaction Systems Furfural-H2?2-Solvent

General information on the reactions of furfurals with hydrogen peroxide is given. We have discussed the Baeyer-Villiger rearrangement of furan 2-hydroxyhydroperoxides and tautomeric transformations with proton transfer of 2-hydroxyfuran and -formylacrylic acid formed in a homogeneous reaction system furfural-H-2?(2)-solvent under the catalysis with the formed acids. The factors affecting these rearrangements and tautomeric transformations as well as their specificity in comparison with benzene type compounds, and the pathway of the reactions of furan aldehydes with H-2?(2) in water have been analyzed. Ketoenol tautomerism of cyclic hemiacetal form of -formylacrylic acid leading to its transformation into succinic anhydride has been described for the first time.