Chemodivergent Ring Annulation of ortho -Bromophenyl Sulfones: Synthesis of π-Expanded Carbazoles and Acridines via Five- and Six-Membered Cyclic Sulfones

Photoredox-catalyzed aminoarylation and thioamination of unactivated alkenes have been developed, providing novel synthetic routes to access synthetically challenging quaternary carbon-centered ben...

Spirocyclizative Remote Arylcarboxylation of Nonactivated Arenes with CO ₂ via Visible-Light-Induced Reductive Dearomatization

External Photocatalyst-Free Visible Light-Promoted 1,3-Addition of Perfluoroalkyl Iodides to Vinyldiazoacetates

Visible-light photoredox-catalyzed selective carboxylation of C(sp3)−F bonds with CO2

Photoredox catalysis can be induced to activate organic substrates or to modulate the oxidation state of transition-metal catalysts via unique single-electron transfer processes, so as to achieve c...

A step-economical method for synthesis of α-CF2H-substituted ketones from readily available alkene feedstocks has been developed. Radical difluoromethylation of aromatic alkenes combining DMSO oxidation and photoredox catalysis is a key to the successful transformation. Electrochemical analysis, laser flash photolysis (LFP), and density functional theory (DFT) calculations reveal that N-tosyl-S-difluoromethyl-S-phenylsulfoximine serves as the best CF2H radical source among analogous sulfone-based CF2H reagents. The present photocatalytic keto-difluoromethylation has been applied to flow synthesis and easily scaled up to gram-scale synthesis within a reasonable reaction time. Furthermore, potentials of the α-CF2H-substituted ketones for useful synthetic intermediates are shown; e.g., synthesis of the CF2H-containing α-hydroxyamide with the same carbon skeleton as that of the anticonvulsant active CF3-analogue, is disclosed. Additionally, mechanistic studies are also discussed in detail.

Red-light absorbing photoredox catalysts offer potential advantages for large-scale reactions, expanding the range of usable substrates and facilitating bio-orthogonal applications. While many red-light absorbing/emitting fluorophores have been developed recently, functional red-light absorbing photoredox catalysts are scarce. Many photoredox catalysts rely on long-lived triplet excited states (triplets), which can efficiently engage in single electron transfer (SET) reactions with substrates. However, triplets of π-conjugated molecules are often significantly lower in energy than photogenerated singlet excited states (singlets). Combined with the inherent low energy of red light, this could limit the reductive/oxidative powers. Here, we introduce a series of sustainable heavy atom-free photoredox catalysts based on red-light absorbing dibenzo-fused BODIPY. The catalysts consist of two covalently linked units: a dibenzo-fused BODIPY fluorophore and an electron donor, arranged orthogonally. Excitation of the dibenzoBODIPY unit induces charge separation (CS) from the donor to the dibenzoBODIPY unit, forming a radical pair (RP) state. Unlike the regular BODIPY counterparts, these catalysts do not form triplets. Instead, SET occurs from the high-energy singlet-born RP states, preventing energy loss and effectively utilizing the low-energy red light. The proximity of donor molecules allows efficient charge separation despite the CS being uphill in energy. The molecules demonstrate efficient catalysis of Atom Transfer Radical Addition (ATRA) reaction, yielding products with high yields ranging from 70 to 90%, while the molecule without a donor group does not exhibit catalytic activity. The mechanistic studies by transient absorption and electron paramagnetic resonance (EPR) spectroscopy methods support the proposed mechanism. The study presents a new molecular design strategy for converting noncatalytic fluorophores to efficient photoredox catalysts operating in the red spectral region.

<div class="abstractSection abstractInFull">\n<p>We have constructed a novel porous pyrene-based organic cage, PyTC1, through the condensation reaction of cyclohexanediamine with 5,5′-(pyrene-1,6-diyl)diisophthalaldehyde. Single-crystal X-ray diffraction analysis reveals the effective intercage C–H...π interaction between cyclohexanediimine and pyrene segments. Such a soft intercage C–H...π interaction, rather than a classic <em>J</em>-aggregate with slipped π–π-stacking configuration, induced an unusual bathochromic shift of pyrene-based chromophore absorption from an ultraviolet region of PyTC1 in solution to the visible light region of PyTC1 in solid-state. This enabled heterogeneous visible light photocatalysis of aerobic hydroxylation of benzeneboronic acid derivatives. To the best of our knowledge, this is the first report that represents an absorption bathochromic shift caused by C–H...π interaction. Such phenomenon could endow visible-light-driven photocatalysis that originally could only be achieved using UV light with the same chromophore.</p>\n</div>\n<p> </p>

Direct quantitative evaluation of complex substances using computer screen photo-assisted technology: The case of red wine

Diverse emission properties of transition metal complexes beyond exclusive single phosphorescence and their wide applications

Comprehensive SummaryHerein, we report an unprecedented molecular editing strategy for cycloketones that involves the precise translocation and removal of single oxygen atom enabled by dual photoexcited palladium and photoredox catalysis. In contrast to conventional ketone molecular editing strategies, which often rely on the loss of pre‐functionalized groups or the addition of additional acylating agents, this approach facilitates the efficient recycling of pre‐functionalized moieties. This is accomplished through a photoexcited palladium catalyzed N–O bond cleavage of cycloketone oxime esters, generating cyanoalkyl radicals and a palladium carboxylate complex. The subsequent photoredox‐catalyzed deoxygenation, mediated by phosphoranyl radicals, then leads to the coupling of cyanoalkyl radicals, ultimately yielding the desired products. This molecular editing strategy features good atom economy due to precise skeletal modifications, broad compatibility with various functional groups, and significant potential for late‐stage functionalization of pharmaceutical derivatives.

The applicability of a heteroaromatic photoredox catalyst in an additive-free photo-mediated hydroamination of stilbenes is described. Initiated by the excitation of a highly potent organic pyrimidopteridine photoredox catalyst (E*[PrPPT*/PrPPT·–] = +2.10 V vs SCE in MeCN), the photo-mediated hydroamination of stilbenes was enabled using unprotected, primary aliphatic, allylic, benzylic amines for the synthesis of various α-phenyl phenethylamine derivatives. Notably, the stereogenic center of α-chiral amines was fully preserved. Both starting materials serve as competent quenching partners. Fluorescence- and competitive fluorescence-quenching experiments as well as electron paramagnetic resonance spectroscopic analysis and density functional theory calculations allowed a plausible reaction mechanism to be deduced.

Transition-metal-catalyzed C–H functionalization is already a useful tool in organic synthesis, whilst the rapid development of photoredox catalysis provides new pathways for C–H functionalization with high selectivity and efficiency under mild reaction conditions. In this review, recent advances in C–H functionalization through merging transition­-metal catalysis with photoredox catalysis are discussed. 1 Introduction 2 Merging Nickel Catalysis with Photoredox Catalysis 3 Merging Palladium Catalysis with Photoredox Catalysis 4 Merging Cobalt Catalysis with Photoredox Catalysis 5 Merging Photoredox Catalysis with Other Transition-Metal Catalysis­ 6 Conclusions

Doping of polycyclic aromatic hydrocarbons (PAHs) with boron and/or nitrogen is emerging as a powerful tool to tailor the electronic structure and photophysical properties. As N‐ doped analogues of anthracene, N,N ‐dihydrophenazines play important roles as redox mediators, battery materials, luminophores, and photoredox catalysts. Although benzannulation has been used successfully as a structural constraint to control the excited state properties, fusion of the N‐aryl groups to the phenazine backbone has rarely been explored. Herein, we report the first examples of dihydrophenazines, in which the N‐aryl groups are fused to the phenazine backbone via B←N Lewis pair formation. This results in structural rigidification, locking the molecules in a bent conformation, while also modulating the electronic structure through molecular polarization. B─N fusion in BNPz1−BNPz3 induces a quinoid resonance structure with significant C─N(py) double bond character and reduces the antiaromatic character of the central pyrazine ring. Borylation also lowers the HOMO/LUMO (highest occupied/lowest unoccupied molecular orbital) energies and engenders bathochromic shifts in the emission. Further rigidification in the solid state gives rise to enhanced emission quantum yields, consistent with aggregation‐induced emission enhancement (AIEE) observed upon water addition to solutions in tetrahydrofuran (THF). The demonstrated structural control and fine‐tuning of optoelectronic properties are of great significance to potential applications as emissive materials and in photocatalysis.

A strategy for overcoming the limitation of the Morita–Baylis–Hillman (MBH) reaction, which is only applicable to electron-deficient olefins, has been achieved via visible-light induced photoredox catalysis in this report. A series of non-electron-deficient olefins underwent the MBH reaction smoothly via a novel photoredox-quinuclidine dual catalysis. The in situ formed key β-quinuclidinium radical intermediates, derived from the addition of olefins with quinuclidinium radical cations, are used to enable the MBH reaction of non-electron-deficient olefins. On the basis of previous reports, a plausible mechanism is suggested. Mechanistic studies, such as radical probe experiments and density functional theory (DFT) calculations, were also conducted to support our proposed reaction pathways.