Rearrangements vs Fragmentations in the Dye-sensitized Photooxygenation of N-Aryl α-Furanamides

The reaction of variously N-substituted α-furanamides with singlet oxygen has been examined. In addition to the expected fragmentation products the reaction affords rearranged 5-hydroxy- and 5-aryloxy-2(5H)-furanones. Products distribution depends on diverse factors: the presence of α-hydrogen, the presence of the amidic group, the nature and the number of nitrogen substituents. The rearrangement to 5-aryloxy-2(5H)-furanones is unreported.