Photocatalytic Fluorosulfonylation/Fluorosulfonamidation of N-Homoallyl Aldehyde Hydrazones to Access FSO₂-/FSO₂N-Functionalized Tetrahydropyridazines

Sulfonyl/sulfamoyl fluoride and tetrahydropyridazine cores represent pivotal structural units in chemical and medicinal science. We herein disclose a photocatalytic strategy for the fluorosulfonylation/fluorosulfonamidation of N-homoallyl aldehyde hydrazones using FABI (1-fluorosulfonyl-2-arylbenzoimidazolium triflate salts) and NFSAP (N-fluorosulfamoylpyridinium salts), enabling efficient access to sulfonyl-/sulfamoyl-substituted tetrahydropyridazines. This protocol demonstrates excellent synthetic scalability and facilitates diverse postderivatization reactions, including SuFEx click reactions and elimination processes. Preliminary mechanistic studies reveal that the transformation proceeds via a fluorosulfonyl/fluorosulfonamidyl radical-mediated cascade cyclization pathway.