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We report the development of a practical photocatalytic strategy to access various nitro‐containing cyclic compounds from olefins via semipinacol‐type rearrangement, cycloetherification, and lactonization reactions, employing N‐nitrosuccinimide as a bench‐stable, non‐metal‐based nitrating reagent. Mechanistic insights suggest that this light‐driven process occurs via NO2 radical pathway mediated by a photoredox catalyst, which triggers an N−N bond fragmentation. Subsequent Giese‐type addition of nitryl radicals to activated olefins takes place, leading to the formation of nitro‐containing β‐functionalized ketones, lactones and cycloethers. The reaction proceeds under mild reaction conditions and tolerates a wide range of functional groups and structural variations. [ABSTRACT FROM AUTHOR]

The incorporation of the gem‐difluoromethylene (CF2) group into organic frameworks is highly sought due to the influence of this unit on the physicochemical and pharmacological properties of molecules. Herein we report an operationally simple, mild, and switchable protocol to access various gem‐difluoro compounds that employs chlorodifloroacetic anhydride (CDFAA) as a low‐cost and versatile fluoroalkylating reagent. Detailed mechanistic studies revealed that electron‐transfer photocatalysis triggers mesolytic cleavage of a C−Cl bond generating a gem‐difluoroalkyl radical. In the presence of alkene, this radical species acts as a unique intermediate that, under solvent‐controlled reaction conditions, delivers a wide range of gem‐difluorinated γ‐lactams, γ‐lactones, and promotes oxy‐perfluoroalkylation. These protocols are flow‐ and batch‐scalable, possess excellent chemo‐ and regioselectivity, and can be used for the late‐stage diversification of complex molecules. [ABSTRACT FROM AUTHOR]

The incorporation of the gem‐difluoromethylene (CF2) group into organic frameworks is highly sought due to the influence of this unit on the physicochemical and pharmacological properties of molecules. Herein we report an operationally simple, mild, and switchable protocol to access various gem‐difluoro compounds that employs chlorodifloroacetic anhydride (CDFAA) as a low‐cost and versatile fluoroalkylating reagent. Detailed mechanistic studies revealed that electron‐transfer photocatalysis triggers mesolytic cleavage of a C−Cl bond generating a gem‐difluoroalkyl radical. In the presence of alkene, this radical species acts as a unique intermediate that, under solvent‐controlled reaction conditions, delivers a wide range of gem‐difluorinated γ‐lactams, γ‐lactones, and promotes oxy‐perfluoroalkylation. These protocols are flow‐ and batch‐scalable, possess excellent chemo‐ and regioselectivity, and can be used for the late‐stage diversification of complex molecules. [ABSTRACT FROM AUTHOR]

We report a mild and operationally simple trifluoroacylation strategy of olefines, that utilizes trifluoroacetic anhydride as a low‐cost and readily available reagent. This light‐mediated process is fundamentally different from conventional methodologies and occurs through a trifluoroacyl radical mechanism promoted by a photocatalyst, which triggers a C−O bond fragmentation. Mechanistic studies (kinetic isotope effects, spectroelectrochemistry, optical spectroscopy, theoretical investigations) highlight the evidence of a fleeting CF3CO radical under photoredox conditions. The trifluoroacyl radical can be stabilized under CO atmosphere, delivering the trifluoroacetylation product with higher chemical efficiency. Furthermore, the method can be turned into a trifluoromethylation protocol by simply changing the reaction parameters. Beyond simple alkenes, this method allows for chemo‐ and regioselective functionalization of small‐molecule drugs and common pharmacophores. [ABSTRACT FROM AUTHOR]

We report a mild and operationally simple trifluoroacylation strategy of olefines, that utilizes trifluoroacetic anhydride as a low‐cost and readily available reagent. This light‐mediated process is fundamentally different from conventional methodologies and occurs through a trifluoroacyl radical mechanism promoted by a photocatalyst, which triggers a C−O bond fragmentation. Mechanistic studies (kinetic isotope effects, spectroelectrochemistry, optical spectroscopy, theoretical investigations) highlight the evidence of a fleeting CF3CO radical under photoredox conditions. The trifluoroacyl radical can be stabilized under CO atmosphere, delivering the trifluoroacetylation product with higher chemical efficiency. Furthermore, the method can be turned into a trifluoromethylation protocol by simply changing the reaction parameters. Beyond simple alkenes, this method allows for chemo‐ and regioselective functionalization of small‐molecule drugs and common pharmacophores. [ABSTRACT FROM AUTHOR]

We leverage the slow liberation of nitrogen dioxide from a newly discovered, inexpensive succinimide‐derived reagent to allow for the C−H diversification of alkenes and alkynes. Beyond furnishing a library of aryl β‐nitroalkenes, this reagent provides unparalleled access to β‐nitrohydrins and β‐nitroethers. Detailed mechanistic studies strongly suggest that a mesolytic N−N bond fragmentation liberates a nitryl radical. Using in situ photo‐sensitized, electron paramagnetic resonance spectroscopy, we observed direct evidence of a nitryl radical in solution by nitrone spin‐trapping. To further exhibit versatility of N‐nitrosuccinimide under photoredox conditions, the late‐stage diversification of an extensive number of C−H partners to prepare isoxazolines and isoxazoles is presented. This approach allows for the formation of an in situ nitrile oxide from a ketone partner, the presence of which is detected by the formation of the corresponding furoxan when conducted in the absence of a dipolarophile. This 1,3‐dipolar cycloaddition with nitrile oxides and alkenes or alkynes proceeds in a single‐operational step using a mild, regioselective, and general protocol with broad chemoselectivity. [ABSTRACT FROM AUTHOR]

Keywords: alkenes; C-H nitration; photoredox; radicals; reaction mechanisms Furthermore, using in situ photo-sensitized, electron paramagnetic resonance spectroscopy, clear evidence for a nitryl radical in solution by nitrone spin-trapping was obtained. Alkenes, C-H nitration, photoredox, radicals, reaction mechanisms. [Extracted from the article]