Ir-Catalyzed Intermolecular Arylthiocyanation of Alkenes

Aims: Organic thiocyanates are important pharmaceutical intermediates. This study aimed to develop a selective and efficient approach for synthesizing organic thiocyanates.

Methods: Under mild reaction conditions, an array of alkenes, KSCN, and diaryliodonium salts are considered good substrates, providing various aryl-substituted alkylthiocyanates with modest to excellent yield. Radical trapping and nucleophilic trapping experiments were carried out to explore the mechanistic pathways. The experiments indicated the involvement of free-radical and carbenium ion intermediate processes. Diaryliodonium salts were used as the radical arylating reagent, and KSCN was the electrophilic cyanating reagent. Under irradiation, the excited photocatalyst reduced aryldiazonium salt to aryl radical. Then, the radical was added to olefin to generate a new radical. Finally, the generated radical was further oxidized and arrested by SCN anion.

Conclusion: This coupling reaction provides a straightforward and practical route to construct various aryl-substituted alkylthiocyanates.