Manganese‐Catalyzed Redox‐Neutral Thiolation of Alkyl Halides with Thioformates

Abstract

Transition metal‐catalyzed C−S cross‐coupling has emerged as an important strategy to furnish thioethers; however, the dominant utilization of noble metal catalysts as well as the construction of challenging C(sp3)−S bonds by transition metal‐catalysis remain highly problematic. Earth‐abundant manganese has gathered increasing interest as an attractive catalyst for new reaction development; nevertheless, C(sp3)−S cross‐coupling reaction by manganese catalysis has not been reported. Herein, we disclose a highly efficient manganese‐catalyzed redox‐neutral thiolation of a broad range of alkyl halides with thioformates as practical sulfuration agents. Strategically, employing easily synthesized thioformates as thiyl radical precursors allows access to various aryl and alkyl thioethers in good to excellent yields. Notably, this redox‐neutral method avoids the utilization of strong bases, external ligands, forcing reaction conditions, and stoichiometric manganese, thus presenting apparent advantages, such as broad substrate scope, excellent functional group compatibility, and mild reaction conditions. Finally, the utilities of this method are also illustrated by downstream transformations and late‐stage thiolation of structurally complex natural products and pharmaceuticals.

Nickel-free cross-electrophile coupling of unactivated alkyl bromides with thiosulfonates and sulfinyl sulfones

“…18 The current state-of-the-art mechanism for nickelcatalyzed reductive thiolation of organic halides has highlighted that in situ generated active Ni developed a highly efficient thiyl radical-mediated thiolation of alkyl halides with thioformates in the presence of Mn catalysis. 20 Meanwhile, our group discovered that Zn played a unique role in the activation of electrophilic thiolating reagents to generate a nucleophilic zinc thiolate, which could thiolate a series of alkyl electophiles. 21 Based on these critical findings, we wondered whether a nickel catalysis-free thiolation could be achieved if nucleophilic zinc thiolate was formed directly from the insertion of a S-S bond in redoxactive thiosulfonates.…”