Batch and flow electrochemical synthesis of allyl sulfones via sulfonation of allyl trifluoroborates: a robust, regioselective, and scalable approach

Abstract

This work describes the electrochemical synthesis of allyl sulfones via sulfonation of allyl trifluoroborates. The process involves a radical addition to the alkene followed by the elimination of the trifluoroborate moiety, giving access to different substituted allyl sulfones. The efficacy of this reaction is attributed to the β-σ(C–B) stabilization of the electrochemically-generated intermediate carbocation, which plays a pivotal role in enforcing regioselectivity during the process. The reaction system is robust and general, allowing for compatibility with aromatic, heteroaromatic, and aliphatic sulfinate and allylic systems. The protocol is considered an inexpensive, safe, and environmentally friendly method for synthesizing this recognizable organic motifs in both synthetic and medicinal chemistry in absence of mediators or even additional supportive electrolite, as only electrons applied through electrical current are required for the reaction to proceed. Moreover, the continuous flow conditions, which fits into green chemistry standards, have demonstrated the feasibility of electrochemically synthesizing allyl sulfones, resulting in highly favorable outcomes and enabling the potential scalability of the electrochemical process.