N-Sulfinyl Phthalimides as Modular Sulfinyl Radical Precursors: PRE-Guided Chemoselective Alkene Difunctionalization and Radical Cross-Coupling.

Despite the importance of sulfoxides in synthesis and biology, the utilization of sulfinyl radicals for their construction remains underexplored compared to other sulfur-centered radicals. While the Persistent Radical Effect (PRE) offers a powerful framework to harness these stabilized species for radical-radical cross-coupling, the development of general transformations is rare due to the lack of modular sulfinyl radical precursors. Herein, we report N-sulfinyl phthalimides as bench-stable, modular precursors that selectively liberate persistent sulfinyl radicals upon single-electron reduction. This strategy enables the first general 1,2-trifluoromethyl-sulfinylation of unactivated alkenes and robust PRE-guided cross-couplings with diverse alkyl radicals derived from C-H bonds, Hantzsch esters, or carboxylic acids. Furthermore, we report the first generation of unsymmetrical sulfinyl sulfones and elucidate a mechanism driven by their rapid tautomerization, enabling a catalyst-free, ambient-temperature protocol for the direct conversion of sulfinate salts into sulfoxides. The broad utility of these protocols is demonstrated by the successful difunctionalization of ethylene gas and the late-stage modification of complex medicinal compounds, alongside versatile product derivatizations. This work establishes a versatile platform for radical sulfinylation governed by precise kinetic control.