Spiroketals of monosaccharides by dye-sensitized photooxygenation of furyl ketoses

- The photooxygenation of novel sugar-furans followed by sulfide reduction is reported.
- Novel spiroketals of monosaccharides are synthesized through a one-pot procedure.
- The synthetic strategy presented for spiro compounds is based on a green process.
- The synthesis of novel furyl ketoses is depicted.

[4+2] Cycloaddition of singlet oxygen to suitably substituted furans followed by reduction of the corresponding endoperoxides afforded functionalized enediones which quickly cyclized into the titled spiroketals. The reported method represents a green synthetic one-pot procedure for novel [6,6]-, [5,6]-, and [5,5]-spiroketals of sugars.