Singlet-Oxygen-Induced Rearrangement of Furan Derivatives

Upon exposure to singlet oxygen and dimethylsulfide, the addition products between 3-furaldehydes and Grignard reagents undergo an oxidative rearrangement to give 2-substituted 3-furaldehydes, in yields ranging from 26-83%. N-Aryl- and N-tosylpyrroles were similarly obtained if the corresponding nitrogen-containing precursors were used instead, in equally attractive yields (64-92%).