Direct Sulfonation of Aryl Boronic Acids using Potassium Disulfite as a SO₂ Source

Potassium disulfite is mainly used for a food additive such as an antioxidant and antimicrobial. Recently, it has also been used as a sulfone source in organic synthesis. For example, Shavnya et al. have performed (CH₃CN)₂PdCl₂ / t-BuXPhos complex catalyzed direct sulfonation from aryl boronic acids and alkyl halides using potassium disulfite as a sulfone source. In this reaction, aryl- and hetero-aryl boronic acids can be applied to this transformation and the related aryl-alkyl sulfones are given. In this way, potassium disulfite is expected to be widely used as an easy-to-use sulfone source.¹⁾