Catalytic disproportionation via carbonate redox tags – a unified strategy for mild hydrogenolysis and oxidations of C–O bonds

Oxygenated molecules are omnipresent in natural as well as artificial settings making the chemical modification of C–O bonds a central tool for their processing. The catalytic hydrogenolysis and oxidation of C–O bonds are particularly important reactions in this context. However, the required (super)stoichiometric terminal redox equivalents which traditionally include highly reactive and hazardous reagents pose multiple practical challenges including process safety hazards, functional group incompatibilities and special waste management requirements. Here, we report a mild Ni-catalyzed disproportionation strategy based on carbonate redox tags for redox transformations of various oxygenated hydrocarbons in the absence of any external redox equivalents or other additives. The purely catalytic process enables the hydrogenolysis of strong C(sp2)–O bonds including that of enol carbonates as well as the catalytic oxidation of C–O bonds at room temperature, underscoring the unusually efficiency of this strategically distinct reactivity. In addition, we investigated the underlying mechanism and provided key insights about such underexplored processes. Further, we show that the studied carbonates have potential as redox active protecting groups. Finally, due to their complete homogeneity, the reactions can be readily downscaled without any adjustments and are compatible with a fluorescence-based reactivity assay. More broadly, the work herein demonstrates the untapped potential of redox tags in organic synthesis and provides the necessary mechanistic understanding for future advancements in this emerging research area.