Iron-catalyzed thiolation of C(sp3)–H with sulfonyl chlorides via photoinduced ligand-to-metal charge transfer†

Abstract

The construction of C(sp³)–S bonds through C(sp³)–H activation holds significant value in the synthesis of sulfides. However, the vast majority of strategies primarily involve the use of electron-rich sulfur sources (such as sulfinates and thioalcohols) to thiolate activated and thermodynamically favored C(sp³)–H bonds. Therefore, further expanding the substrate range of sulfur sources and various C(sp³)–H bonds would provide an entry for the synthesis of unique structural molecules. Here, we report a FeCl₃/HCl synergistic catalytic approach that enables the formation of C(sp³)–S bonds via reductive deoxygenation cross-coupling of activated/inert C(sp³)–H and aryl/alkyl sulfonyl chlorides without the need for external reductants. Mechanism studies reveal that HCl plays a crucial role in the thiolation of inert C(sp³)–H bonds, not only enhancing the catalytic activity of FeCl₃ but also forming electron donor–acceptor (EDA) complexes with sulfonyl chlorides.