Photoinduced Deacylative Radical C−C and C−S Couplings of Unstrained Ketones

Abstract

The homolytic fragment of the adjacent C(sp³)–C(sp²) bonds in unstrained ketones has proven to be a formidable challenge. Traditional methods for C(sp³)–C(sp²) bond activation typically require harsh reaction conditions, transition-metal catalysts, or specifically designed strained substrates, which largely limit their practical application in organic synthesis. In this study, we develop a visible light photoinduced deacylative C−C and C−S couplings of ketones under mild conditions. This approach leverages the unique reactivity of dihydroquinazolinones, which are easily accessible from commercially available ketones. Upon visible light irradiation, these precursor compounds undergo controlled homolysis to generate open-shell radical species, thereby circumventing the high bond dissociation energy that typically hinders the cleavage of C(sp³)–C(sp²) bonds. The resulting carbon-centered radicals then engage in synthetically diverse cascade reactions with various sulfonyl coupling partners, including sulfonyl oximes, heteroaryl sulfones, and sodium arylsulfinates, enabling the efficient construction of C–C and C–S bonds. This strategy features mild reaction conditions, high efficiency, broad substrate scope and readily accessible starting materials. Mechanistic studies reveal that the process follows a non-chain radical mechanism, where dihydroquinazolinones undergo single-electron transfer (SET) with the excited-state photocatalyst, generating reactive alkyl radicals that engage in subsequent reactions. By transforming simple ketones into versatile radical precursors, our method provides a new platform for reaction design and late-stage functionalization, offering chemists a valuable tool for constructing complex molecular architectures from unstrained ketones.

Keywords

Unstrained ketones / Photoinduced deacylation / Deacylative transformation / C–S coupling / Single-electron transfer / Sulfonyl oximes / Dihydroquinazolinones / Alkyl radicals

RIGHTS & PERMISSIONS

2025 SIOC, CAS, Shanghai, & WILEY-VCH GmbH