Strain-Release Functionalization of N-Aryl Bicyclo[1.1.0]butane Sulfonamides to Access Spirocyclic Sultams

Sultams are recognized as important scaffolds in drug discovery and medicinal chemistry. When integrated into spirocyclic structures, especially those containing cyclobutane units, they provide conformational rigidity and a well-defined three-dimensional structure, which enhances their physicochemical and pharmacokinetic properties. Despite their potential, the synthesis of spirocyclobutyl sultams has been scantly explored. In this study, we present a general strategy for synthesizing spirocyclobutyl benzosultams by combining the strain release of N-aryl bicyclo[1.1.0]butane sulfonamides with photoredox catalysis. This method enables the construction of a diverse library of functionalized spirocyclobutyl benzosultams by incorporation of a wide range of radicals, including SCF₃, SCN, SO₂R, and P(O)(OR)₂.