Synthesis of branched allylic sulfones by regioselective boron-catalysed hydrosulfonylation

Branched allylic sulfones are scaffolds widely distributed in bioactive molecules and organic functional materials. The synthesis of allylic sulfones has been developed, e.g., using the Tsuji-Prost reaction, hydrosulfonylation and radical addition reactions, yet the hydrosulfonylation of unactive 1,3-diene without transition metals has been rarely explored. Here we synthesized branched allylic sulfones by boron-catalysed highly regioselective hydrosulfonylation of 1,3-diene with sulfinic acid, without transition metal catalysts. Compared with the previous methods, the advantages include readily available starting materials without pre-treatment; cheap boron trifluoride etherate; simple operation and easy scaling-up; the reaction does not require dry conditions, an inert atmosphere or a water scavenger; and excellent atom economy and regioselectivity.