Site-Selective Late-Stage C–H Functionalization via Thianthrenium Salts

Abstract The high abundance of C–H bonds in organic molecules makes C–H functionalization a powerful approach to quickly increase the complexity of an organic molecule. However, the high abundance of C–H bonds also provides a challenge to C–H functionalization reactions: selectivity. While most C–H functionalization reactions produce mixtures of different products for most substrates, we have developed a highly selective method for aromatic C–H functionalization via sulfonium salts. The reaction does not require a certain directing group to be selective. The introduced functional group is a sulfonium group, which participates in various follow-up reactions such as palladium-catalyzed cross-coupling reactions and photoredox catalysis. Here we discuss our pathway to develop the reaction as well as its scope and utility. 1 Introduction 2 Site-Selective Synthesis of Sulfonium Salts 3 Sulfonium Salts in Palladium-Catalyzed Cross-Coupling 4 Sulfonium Salts in Photoredox Catalysis 5 Sulfur(IV) Reductive Elimination 6 Cine Substitution 7 Conclusion