Scope and Limitations of the Photooxidations of 2-(α-Hydroxyalkyl)furans: Synthesis of 2-Hydroxy-exo-brevicomin

Photooxygenation of 2-(alpha-hydroxyalkyl)furans at 5 degrees C in MeOH followed by in situ reduction affords, in one synthetic operation, 6-hydroxy-3(2H)-pyranones and/or 5-hydroxy-2(5H)-furanones. The relative ratio of the final products is highly dependent on the substitution of the starting furan substrate. Photooxygenation of 2-(alpha,beta-dihydroxyalkyl)furans followed by in situ reduction and ketalization with acid rapidly provides the 6,8-dioxabicyclo[3.2.1]oct-3-en-2-one framework. This new methodology was successfully applied to the synthesis of 2-hydroxy-exo-brevicomin.