An efficient Petasis olefination of sugar lactones under continuous-flow
microwave conditions was developed. Their conversion into exo-glycals can be steered by adjusting
the residence time and the concentration of the solution within
the reactor. Applying a continuous-flow procedure, the reaction
time can be shortened to less than three minutes, several hundred
times shorter compared to values given in the literature for batch
procedures. This setup is utilizable for a gram-scale synthesis
of enol ethers and exo-glycals, in particular,
such ones containing potentially (Lewis) acid sensitive acetalic
protecting groups.
Petasis olefination - continuous-flow reactions -
exo-glycals - sugar lactones - microwave support