Click chemistry reaches a new dimension

In 2014, K. Barry Sharpless and coworkers at Scripps Research Institute California developed sulfur fluoride exchange (SuFEx), a simple and rapid click chemistry reaction that uses sulfuryl fluoride (SO₂F₂) to make carbon-sulfate links. They used the technique to synthesize disulfates, polysulfate polymers, and other linear products. Suhua Li, Sharpless, and coworkers have now devised a variation that kicks SuFEx click chemistry into another dimension. Using thionyl tetrafluoride (SOF₄) instead of SO₂F₂ as a SuFEx reagent enables them to make up to three tetrahedrally oriented connections to each sulfur hub molecule instead of two linear linkages (Angew. Chem. Int. Ed. 2017, DOI: 10.1002/anie.201611048). Thionyl tetrafluoride reacts initially with a primary amino group, forming a tetrahedral iminosulfur product with two fluoride “handles.” One fluoride or both can then react with aryl alcohols or alkyl amines to create products that are doubly or triply substituted along the sulfur hub’s tetrahedral axes. Potential applications include the synthesis of functional polymers and small-molecule enzyme inhibitors.