Electron Donor–Acceptor Complex Enabled Radical Cyclization of α-Diazodifluoroethyl Sulfonium Salt with Unactivated Alkynes
Mingyue He, Xiaodong Tang, Hao-Yan Wu, Jing Nie, Jun‐An Ma, Fa‐Guang Zhang
Abstract
An α-diazodifluoroethane sulfonium reagent was developed in this study to undergo [3 + 2] radical cyclization with unactivated alkynes to give the corresponding 3-difluoromethyl pyrazoles under blue light irradiation conditions. The key to the success of this transformation lies in the formation of an electron donor-acceptor (EDA) complex between an electron-deficient α-diazo sulfonium salt and an electron-rich triaryl amine. This study circumvents a major substrate scope limitation in polar cycloaddition reactions of existent diazodifluoroethane reagents.
Topics & Concepts
SulfoniumChemistryDiazoReagentElectron acceptorSalt (chemistry)PhotochemistryAmine gas treatingAcceptorSubstrate (aquarium)Electron donorRadical ionCycloadditionCombinatorial chemistryMedicinal chemistryOrganic chemistryIonCatalysisPhysicsGeologyOceanographyCondensed matter physicsFluorine in Organic ChemistryCyclopropane Reaction MechanismsCatalytic C–H Functionalization Methods