Thianthrenium-enabled sulfonylation via electron donor-acceptor complex photoactivation

Sulfone-containing compounds are prevalent building blocks in pharmaceutical agents and other biomolecules, and they serve as key intermediates in the synthesis of complex scaffolds. During the past decade, several methods have been developed to access sulfones. These strategies, however, require the use of strong reaction conditions, limiting their substrate scope. Recently, visible-light-mediated transformations have emerged as novel platforms to access unprecedented structural motifs. This report demonstrates thianthrenium-enabled sulfonylation via intra-complex charge transfer to generate transient aryl- and persistent sulfonyl radicals that undergo selective coupling to generate alkyl- and (hetero)aryl sulfones under ambient conditions. This strategy allows retention of halide handles, presenting a complementary approach to transition metal-mediated photoredox couplings. Furthermore, this sulfonylation allows high functional group tolerance and is amenable to late-stage functionalization of complex biomolecules. Mechanistic investigations support the intermediacy of electron donor-acceptor (EDA) complexes.