Generation of Heteroaryl-Substituted Sulfonyl Compounds from Sulfur Dioxide via Remote Heteroaryl ipso-Migration.

The generation of heteroaryl-substituted sulfonyl compounds via a catalyst-, base-, and additive-free three-component reaction of heteroaryl-substituted tertiary alcohols, aryldiazonium tetrafluoroborates, and DABCO·(SO2)2 under mild conditions is developed. Various functional groups are tolerated well in this transformation, and a broad substrate scope is demonstrated. A preliminary mechanistic investigation shows that this reaction undergoes a radical process, including the insertion of sulfur dioxide, sulfonyl radical addition to unactivated alkene, and remote heteroaryl ipso-migration.