Photo‐Triggered Self‐Induced Homolytic Dechlorinative Sulfonylation/Cyclization of Unactivated Alkenes: Synthesis of Quinazolinones Containing a Sulfonyl Group

Abstract

A self‐photocatalyzed sulfonylation/cyclization of quinazolinones containing unactivated alkenes with various sulfonyl chlorides was developed. The protocol provides access to sulfonyl radicals via energy transfer from the quinazolinone skeleton to the sulfonyl chloride. Notably, the transformations proceeded without any external photocatalysts, additives, or oxidants, providing an alternative method for fabricating sulfonylated compounds.

Recent advances in the synthesis of 2,3-fused quinazolinones

“…17 Jin et al disclosed a photo-triggered self-catalyzed and energy transfer (EnT) strategy for the construction of sulfonated 2,3-fused quinazolinones 23 in good yields (Scheme 11). 18 The reaction did not require any external photocatalysts, additives or oxidants. The sulfonyl radicals were obtained via energy transfer from the quinazolinone skeleton to the sulfonyl chloride 22 , which then reacted with alkenyl quinazolinones 21 to afford quinazolinones containing a sulfonyl group in good yields (Scheme 11).…”

“…It is noteworthy that the products were obtained with high diastereoselectivity. This method provides a green and efficient way to synthesize polycyclic quinazolinones and valuable drug molecules.A plausible reaction mechanism for [4 + 2]/[3 + 2] tandem cycloaddition was proposed based on18 O-labeled experiments (Scheme 48). Pd(II) initiated C-H bond activation to form palladacycle Int-88, which underwent an insertion to alkyne to give Int-90 via Int-89.…”

Photocatalyst-, metal- and additive-free regioselective radical cascade sulfonylation/cyclization of benzimidazole derivatives with sulfonyl chlorides induced by visible light

“…In the past few years, photocatalytic strategies without an external photosensitizer have attracted tremendous attention because of their excellent atom economy and sustainability. To date, most of the methods established under photocatalyst-free conditions have proceeded via an energy transfer (EnT) 13 or electron-donor–acceptor (EDA) 14 process. Herein, under photocatalyst- and additive-free conditions, we report an efficient photocascade protocol toward the synthesis of numerous sulfonylated benzimidazole derivatives without the involvement of an EnT or EDA process, which is operationally simple and carried out under mild and neutral conditions.…”

Access to Phosphine-Containing Quinazolinones Enabled by Photo-Induced Radical Phosphorylation/Cyclization of Unactivated Alkenes

“…More recently, remarkable achievements have been made in photo-induced radical addition/cyclization of unactivated alkenes to furnish quinazolinone derivatives. Representative studies include difluoromethylation/cyclization reactions disclosed by Wu’s group and alkylation, fluoroalkylation, acylation, and sulfonylation/cyclizations reported by Jin’s group (Scheme c). These methodologies all enable access to biologically important ring-fused quinazolinones bearing various functional groups in a mild and efficient manner.…”