PIFA-mediated chemo-divergent esterification reaction: access to the synthesis of α-ketoesters and esters from sulfoxonium ylides.

Herein, we report a facile PIFA (bis(trifluoroacetoxy)iodobenzene)-mediated chemo-divergent synthesis of α-ketoesters and simple esters using sulfoxonium ylides and alcohols under mild and metal-free reaction conditions. Sulfoxonium ylides bearing electron-donating groups predominantly afforded α-ketoesters via the direct oxidation of the in situ intermediate, diethoxy acetophenone. In contrast, methoxy substitution and electron-withdrawing substituents led to the formation of simple esters via oxidative chemo-selective (sp2)C-C(sp2) σ-bond cleavage of the in situ intermediate, phenylglyoxal. Remarkably, this methodology represents a group-selective direct synthesis of both α-ketoesters and simple esters separately from sulfoxonium ylides in good to moderate yields, enabling broad functionalization as well as late-stage modifications of drugs and complex alcohols. Mechanistic insights were gained via control experiments, providing a detailed understanding of the reaction mechanism.