Capturing primary ozonides for a syn-dihydroxylation of olefins.

Ozonolysis is a widely used and practical synthetic technique for the deconstructive oxidation of olefins using ozone. While there are numerous ozonolysis reactions that give a myriad of products and functionalities, almost all of them involve scission at the olefin double bond. Using ozone as a constructive reagent rather than a deconstructive one would open new domains of chemical reactivity and amplify molecular complexity in synthetic methodology. Here we report the use of primary ozonides as preparative synthetic intermediates for a safe and green olefin syn-dihydroxylation reaction. Furthermore, we have demonstrated this method using a continuous flow reactor that virtually eliminates peroxide accumulation and extended these applications towards the synthesis of pharmaceutically relevant small molecules such as guaifenesin, the active ingredient in Mucinex, and a precursor to ponesimod, a drug to treat multiple sclerosis.