Visible-light Promoted Iron-Catalyzed Nitrene Transfer Reactions Of Dioxazolones

Transition metal-catalyzed nitrene transfer reaction has emerged as an attractive approach for constructing N-containing compounds and attracted considerable attention from chemists.Compared with azides and iminoiodinanes,dioxazolones as novel,readily available,bench-top stable and easy to handle nitrene precursors have been developed smoothly in organic chemistry.Transition metal-catalyzed nitrene transformation of dioxazolones,which usually involved catalysts such as rhodium,iridium,ruthenium,and cobalt,has been well studied.Therefore,the development of facile and novel catalytic approach for the nitrene transfer reaction of dioxazolones with more readily accessible and cheap catalyst continues to be an important scientific pursuit.In this dissertation,visible-light-promoted iron-catalyzed intermolecular C（sp³）-H amidation with dioxazolones,intermolecular N-arylation of dioxazolones with arylboronic acids and imidation of sulfoxides or sulfides with dioxazolones are described.The detailed research contents are shown as follows:1.The visible-light-promoted iron-catalyzed C（sp³）-H amidation of 1,3-dicarbonyl compounds or diarylmethanes with dioxazolones was developed under exogenous photocatalyst-free conditions.This reaction has the characteristics of cheap and easy-to-obtain catalyst,mild reaction conditions,and high atom economy.The radical capture experiments suggested that the C-H amidation may involved a radical pathway.The kinetic isotope effect experiments demonstrated that the C-H bond cleavage was not the rate-limiting step.Theoretical calculations showed that the activation of dioxazolones could be achieved under mild conditions by the spin interconversion of dioxazolone-bounding iron species via visible-light irradiation,DFT calculations also revealed that the CO₂ extrusion step is rate-limiting step.2.The iron-catalyzed intermolecular N-arylation of dioxazolones with commercially available arylboronic acids was achieved efficiently under visible-light irradiation.Under the optimized reaction conditions,the N-arylation of dioxazolones with various arylboronic acids proceeded smoothly to afford the corresponding products in 42%-99%yields.This method exhibited good functional group tolerance,including methyl,methoxyl,trifluoromethylaryl,nitro,methoxycarbonyl,formyl and halogen（F,Cl and Br）groups.The radical capture experiments suggested that the N-arylation of dioxazolones may involved a radical pathway.Intermediate capture experiments showed that aminoboronate is an intermediate of this reaction.3.The simple iron salt catalyzed imidation of sulfoxides or sulfides with dioxazolones has been investigated under visible-light irradiation without an exogenous photosensitizer.Under the optimized reaction conditions,the imidation of various sulfoxides or sulfides with dioxazolones proceeded smoothly to provide the corresponding sulfoximines or sulfimides in43%-98%yields.The radical capture experiments suggested that the imidation of sulfoxides or sulfides may involve a radical pathway.