Indirect Anti‐Markovnikov Hydrofunctionalization of Terminal Alkenes via an Alkenyl Thianthrenium Intermediate

Abstract The anti‐Markovnikov hydrofunctionalization of terminal, unactivated olefins is an evergreen synthetic challenge in organic chemistry. Several direct and indirect anti‐Markovnikov methods have been developed, ranging from the classical hydroboration/oxidation protocol to state‐of‐the‐art photoredox catalytic, transition‐metal‐complex‐catalyzed, and enzymatic procedures. Despite the ever‐expanding suite of synthetic capabilities, these methods still have limited generality in their substrate scope, especially with nucleophiles. Herein, we show that terminal, unactivated olefins can be transformed into anti‐Markovnikov products via an alkenyl thianthrenium intermediate that undergoes sequential hydride and nucleophile addition. The strategic advantage of this method lies in the ability to utilize a diverse array of oxidatively sensitive nucleophiles as reaction partners. This is accomplished through a mechanistically distinct, two‐stage dication pool anti‐Markovnikov approach, where separate oxidative olefin activation by thianthrenation is followed by the selective generation of a reactive alkyl thianthrenium salt.