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A visible‐light photoredox‐catalyzed three‐component difluoromethylative heteroarylation of unactivated alkenes is reported. This reaction provides a highly efficient and chemo‐selective method for the synthesis of difluoroalkyl‐containing quinoxalin‐2(1H)‐ones by the formation of two new C‐C bonds in single step from readily available starting materials under mild reaction conditions. This three‐component reaction displays a synthetic simplicity, broad substrate scope, and excellent functional group compatibilities. The preliminary mechanistic investigation implies that a radical process was responsible for this three‐component transformation. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A visible‐light‐induced tandem radical intramolecular cyclization/arylation of quinoxalin‐2(1H)‐ones with bromodifluoroacetamides is described. This protocol allows efficient access to a variety of valuable α,α‐difluoro‐γ‐lactam‐fused quinoxalin‐2(1H)‐ones in moderate to good yields under metal‐free, mild and redox neutral reaction conditions. This strategy is tolerant of various functional groups and a broad range of substrates. The mechanism experiments suggested an involvement of 5‐exo‐trig cyclization and a radical process in this transformation. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A visible‐light‐promoteded [3 + 2] cycloaddition reaction of 2H‐azirines with quinones has been developed under mild reaction conditions. The reaction provides a general and efficient strategy for the synthesis of the benzo[f]isoindole‐4,9‐diones scaffold via a tandem [3 + 2] cyclization/oxidative aromatization with molecular oxygen. Furthermore, preliminary studies for photocatalytic properties show that the benzo[f]isoindole‐4,9‐diones 3 can be used as photocatalysts in several organic transformations. [ABSTRACT FROM AUTHOR]

This work reports the photocatalytic application of an anthraquinone‐containing polymeric photosensitizer (AQ‐PHEMA) in the visible light‐induced cross‐dehydrogenative‐coupling of N‐aryl tetrahydroisoquinolines with several nucleophiles, including nitromethane, 1‐methyl‐2‐alkyl ketone and dialkyl (aryl) phosphine oxide. The results revealed that the reaction could be catalyzed by AQ‐PHEMA efficiently to afford a series of 1‐substituted‐2‐aryl‐1,2,3,4‐tetrahydroisoquinolines in good to excellent yields with nice substrate tolerance under aerobic conditions at room temperature. The practical application potential was also showcased by a gram‐scale synthesis. More importantly, the utilization of AQ‐PHEMA as a heterogeneous photosensitizer also showed nice recyclability and reusability of the catalyst, whereas AQ‐PHEMA can be easily separated and reused for at least 8 times without significant loss of photocatalytic activity. [ABSTRACT FROM AUTHOR]

A visible‐light‐induced site selective C−H alkylation of heterocyclic N‐oxides with N‐hydroxyphthalimide esters was developed using Eosin Y as the photocatalyst in the presence of Cs2CO3 under redox‐neutral and mild conditions. Using N‐hydroxyphthalimide esters as the radical precursors, quinoline and pyridine N‐oxides were readily coupled with a wide range of primary, secondary, and tertiary radicals to afford the desired alkylated heterocyclic N‐oxides in moderated to excellent yields. Importantly, this reaction protocol also successfully demonstrated its applications for the construction of glycosyl or bioactive natural dehydroabietic acid containing heterocyclic N‐oxides, as well as the pharmaceutical and agrochemical active alkylated quinine‐based functional molecules (potential antimalarial drug). [ABSTRACT FROM AUTHOR]

A novel fluorescein-containing polymeric photosensitizer (FS-PHEMA) was successfully synthesized and used as an excellent heterogeneous photocatalyst for aerobic photooxidation of thioethers, hydroxylation of aryl boric acids, and oxidative self-coupling of amines. All the reactions could run smoothly upon irradiation of blue LED under aerobic conditions at room temperature. This heterogeneous photosensitizer can be easily separated, recovered, and reused at least 5 times without significant loss of catalytic activity, showing a good potential in practical applications. The fluorescein-containing polymeric heterogeneous photocatalyst (FS-PHEMA) can catalyze the aerobic photooxidation of thioethers, the aerobic photooxidative hydroxylation of aryl boric acids, and the aerobic photooxidative coupling of amines efficiently by visible light to afford a series of sulfoxides, phenols, and imines in good yields with nice substrate tolerance. The gram-scale synthesis indicates the practical application potential of FS-PHEMA. Moreover, this polymeric photocatalyst can be easily separated and reused for 5 times without significant loss of catalytic activity. [Display omitted] [ABSTRACT FROM AUTHOR]