Synthesis of Vinyl and 1,3‐Dienyl Sulfones Enabled by Photochemical Excitation of Halogen‐Bonding Complexes

Abstract

The photochemical catalyst‐free radical‐based synthesis of vinyl and 1,3‐dienyl sulfones is disclosed. Mechanistic investigations support that the transformations rely on a visible‐light‐promoted activation of a halogen‐bonding complex, which is formed between an alkenyl (or 1,3‐dienyl) bromide and a sodium sulfinate salt. The reactions exhibit a wide functional group tolerance (compatible with heteroatoms, electron‐withdrawing and electron‐donating groups), finding application in the structural modification of biologically relevant molecules. Eventually, a continuous flow protocol was developed to upscale these transformations.

Photocatalytic Synthesis and Functionalization of Sulfones, Sulfonamides and Sulfoximines

“…Recently, Plaza and co-workers reported the use of sulfinates as sulfonyl agents through direct irradiation of a halogen-bond complex. [34] Inspired by the ongoing interest in halogen bonding as a new non-covalent interaction for activation of different substrates, [35] the authors described the formation of a halogen bond complex between the sulfinates and alkenyl bromides. This halogen-bond complex, when irradiated, generates the corresponding sulfonyl radical and alkenyl radical, that undergo recombination to generate the final alkenyl sulfones from moderate to excellent yields.…”