Visible-light-promoted O-glycosylation with indolylthio glycosides.

Reducing the energy input of light in photocatalytic reactions is desirable yet challenging, as modifying the light-absorbing or catalytic properties of a photocatalyst typically requires tedious preparation, resulting in a lengthy development process. Here, we overcome this limitation by achieving manganese-based low-energy photoredox catalysis through the in-situ assembly of simple Mn salts with inexpensive coordinating chemicals, thereby bypassing the need for complex pre-preparation. Assembling Mn(acac)2, 2,2'-bipyridine-6,6'-diamine, and TMSN3 in-situ forms a visible-light-absorbing system that, upon blue-light irradiation, generates azido radicals to drive an anti-Markovnikov hydroazidation of unactivated alkenes with H2O as the hydrogen source. Building on this assembly strategy, the combination of Mn(acac)3 and TMSN3 in CH3CN/HFIP yields a system with a light-absorption range extended to 850 nm; this feature is further leveraged to unlock the selective aerobic hydroxyazidation of alkenes in a single step. These findings pave the way for the development of in-situ-assembled, 3 d metal-based low-energy photochemistry.

The direct catalytic functionalization at the C1-position of unprotected tetrahydroisoquinolines (THIQs) remains a challenging task in synthetic chemistry. In this study, we have developed a photocatalytic strategy that utilizes readily available alkyl carboxylic acids as alkylating agents. Under the catalysis of 9-phenylacridine and visible-light irradiation, direct decarboxylative alkylation of unprotected THIQs has been achieved. This method requires no prefunctionalization of substrates and exhibits excellent substrate compatibility with a wide range of carboxylic acids and THIQ derivatives, providing an efficient and versatile approach for the rapid assembly of pharmaceutically active C1-alkylated 3,4-dihydroisoquinoline (DHIQ) skeletons.

Photocatalysis is a powerful tool for the synthesis of organic molecules, yet its widespread application is hindered by the dependence on high-energy light sources and expensive metal-based catalysts, which can limit scalability and environmental sustainability. In this study, we present a modular design strategy for organic dyes engineered for efficient red-light absorption, enabling photocatalytic reactions under low-energy irradiation. Our findings establish a clear relationship between the oxidation potential of the photocatalyst and the nature of its donor moiety, as well as between the reduction potential and the electronic characteristics of its core structure. Moreover, we demonstrate that the E0-0 energy of a photocatalyst can be predicted via multivariate linear regression using the donor's oxidation potential and the core's reduction potential as descriptors. Utilizing this strategy, we synthesized red-light-absorbing photocatalysts that efficiently promote C─heteroatom cross-coupling reactions under mild conditions. This approach overcomes the limitations of blue-light photocatalysis by offering broad substrate compatibility, including π-conjugated aryl bromides and photolabile functional groups, while minimizing undesirable hydrodehalogenation. By reducing reliance on precious metals and improving energy efficiency, our approach provides a scalable alternative to traditional photocatalysis and advances the development of metal-free photocatalysts for sustainable chemistry.

β-Amino ketones are versatile synthetic intermediates present in numerous biologically active compounds. Herein, we report a diastereoselective aminoacylation of β-methylstyrenes using acyl saccharins as bifunctional reagents to access β-amino ketones through cooperative N-heterocyclic carbene (NHC) and photoredox catalysis. The reaction proceeds via single-electron oxidation of the alkene to generate a radical cation, followed by nucleophilic addition and diastereoselective coupling between the resulting carbon-centered radical and an NHC-bound ketyl radical. This scalable method exhibits broad substrate scope and good functional group tolerance. Mechanistic studies support a radical pathway, and a plausible mechanism for this organocatalytic transformation is proposed.

The merger of photoredox catalysis with asymmetric copper catalysis has been successfully achieved, enabling the conversion of simply preactivated achiral alcohols into enantiomerically enriched alkyl nitriles via deoxygenation with organophosphorus(III) compounds. The reaction features mild reaction conditions, a broad substrate scope, high yields, and high enantioselectivities. Moreover, the reaction can be scaled up to synthesize key chiral intermediates to bioactive compounds.

Chemoselective functionalization of hetero-gem-dimetalloid represents an attractive strategy in terms of diversity-oriented synthesis. In particular, desilylative functionalization of gem-silylboronate esters remains a challenging task and existing solutions heavily relied on ionic reactions. Herein, we report a desilylative functionalization of allylic gem-silylboronate esters with aldehydes under synergistic photoredox and chromium(II) catalysis. With different substrates, both α- and γ-functionalization are realized with exclusive regioselectivity and diastereoselectivity, which is dictated by the chair-like transition state of predominant isomer of CrIII allyl intermediate. Moreover, γ-functionalization products bearing CF2 unit are acquired when gem-difluoroalkene-containing substrates are employed. In the presence of chiral ligand, enantioselective allylation of aldehydes is successfully accomplished, affording alkenylated 1,2-diols after oxidative workup with excellent regio-, diastereo- and enantioselectivity. The current protocol displays wide substrate generality and broad functional group compatibility. In addition, diverse post-transformations converted obtained products into a variety of valuable structures.

The defluorinative coupling of fluoroalkenes with carbonyl compounds provides a direct and efficient strategy to valuable allylic alcohols. However, existing methods typically rely on transition-metal catalyst, stoichiometric reductants, or strongly reducing conditions. Herein, we report a photoredox catalyzed defluorinative coupling between fluoroalkenes and aliphatic carbonyls mediated by ligated boryl radicals, enabling the synthesis of both fluorinated and nonfluorinated allylic alcohols dictated by the choice of fluoroalkene substrate. This transition-metal-free protocol operates under mild conditions, exhibiting high Z/E stereoselectivity and broad substrate scope.

Achieving the direct functionalization of chemically inert C(sp3)-H bonds under mild reaction conditions with organocatalysis continues to be a notable challenge in the field of synthetic chemistry. Herein, we report a remote C(sp3)-H acylation of amides via an NHC and photoredox dual-catalyzed mechanism involving a radical 1,5-hydrogen atom transfer (HAT). This method demonstrates a notable broad substrate scope, including amides derived from cyclopentyl, cyclohexyl, and extended alkyl chains, all of which furnished the corresponding products efficiently.

Ring-cleavage reactions of cyclopropyl alcohols are a valuable tool for the synthesis of linear and α- or β-branched ketones. Here, we describe a visible light-induced ring-opening alkylation of these substrates with benzyl, allyl, and secondary alkyl Katritzky salts. The reaction proceeds under dual photoredox and nickel catalysis in the presence of a titanium(IV) isopropoxide additive. Mechanistically, the ring-opening step starts with generation of the cyclopropoxy radical and is followed by its isomerization to the β-carbonyl radical. This enables the regioselective preparation of β-branched ketones from 1,2-disubstituted hydroxycyclopropanes.

Herein we describe a practical synthesis of difluoromethylated selenides enabled by organophotoredox catalysis. A diverse range of functionalized selenides were efficiently constructed from selenosulfonates and commercially available BTSO2CF2H, affording moderate to excellent yields under mild conditions. The protocol features low catalyst loading and operational simplicity. Moreover, this approach has been successfully translated to 18F-difluoromethylation with high radiochemical conversion, thus providing a streamlined route to potential PET imaging agents.

This work describes the design of chiral iron(III) photoredox catalysis for asymmetric radical cation reactions. The newly developed catalysis successfully minimizes the use of chiral sources and exhibits high tunability, thereby enabling a highly enantioselective (4 + 2) cycloaddition of chalcone derivatives. A mechanistic study revealed the details of the cycloaddition steps that account for the observed stereoselectivity. Furthermore, the unique regioselectivity of the radical cation (4 + 2) cycloaddition enabled us to accomplish the first asymmetric total synthesis of (+)-heitziamide A.

Redox photosensitizers are key components in photoredox catalysis, mediating photoinduced electron transfer from an electron donor to a catalyst or substrate. In systems proceeding through reductive quenching, the efficiency of forming the one-electron-reduced photosensitizer critically determines the overall quantum yield. Here, we report a comprehensive photophysical investigation of 4,5,9,10-tetraethyl-1,2-dihydrobenz[de]imidazo[1,2,3-ij]-1,8-naphthridinium cation (N-BAP+), originally developed as a redox photosensitizer for oxidative quenching in photocatalytic organic synthesis. The photochemical reduction of N-BAP+ by 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (BIH) was also analyzed, focusing on the contributions of the singlet and triplet excited states of N-BAP+. Spectroscopic studies demonstrate that N-BAP+ undergoes efficient reductive quenching with BIH, generating the one-electron-reduced species N-BAP˙. Based on these findings, we applied N-BAP+ to photocatalytic CO2 reduction using a Mn-complex catalyst and BIH as a reductant, resulting in an efficient and durable photocatalytic CO2 reduction system. Kinetic analysis revealed that the reductive quenching of the triplet excited state was the essential pathway governing the activity of this photocatalytic CO2 reduction. These findings suggest that numerous candidates, with or without TADF properties, could serve as organic redox photosensitizers free of heavy metal ions. For optimal performance, such molecules should achieve as high a triplet excited-state formation yield as possible while keeping the singlet excited-state lifetime as short as possible.

Despite growing interest in 3d transition metals for photoredox catalysis, manganese remains markedly underexplored in this domain. The advancement of Mn-based photochemical asymmetric transformations has been significantly hindered by the metal's extensive range of accessible oxidation states (from -3 to +7), intricate excited-state redox behavior, and the propensity to form highly reactive transient species─factors that collectively undermine precise stereochemical control. To overcome these limitations, we introduce a synergistic dual-catalytic system that integrates a unique Mn(IV)/Mn(III) dual-excitable complex featuring N-heterocyclic carbene (NHC) ligands with a chiral cobalt bisoxazoline complex. This well-defined manganese complex enables mechanistically distinct and controllable radical pathways through excitation at different oxidation states─Mn(IV)* and Mn(III)*─allowing each excited state to be selectively harnessed with cobalt-mediated stereocontrol. This adaptive strategy facilitates two challenging enantioselective transformations: asymmetric alkylation of acyclic α-imino esters to construct quaternary stereocenters, and enantioselective protonation to form tertiary stereocenters. A wide range of α-tertiary and α-secondary amino acid derivatives were obtained in up to 99% yield with excellent enantioselectivity (up to 99:1 er). Notably, the system exhibits pronounced nonlinear stereochemical amplification, delivering high-fidelity enantioselection (up to 99:1 er) even when using a partially enriched chiral ligand (65:35 er). By leveraging earth-abundant metals and visible-light activation, our approach provides a sustainable and versatile platform for synthesizing high-value chiral building blocks, with promising implications for pharmaceutical and materials science.

A photo-induced remote and selective C(sp 3 )–H cyanation and deuteration reaction of amide is herein reported.

Tunable pyridinium catalysts with redox activity and Lewis acidity, facilitate photocatalytic oxidations, bond cleavages, and tandem transformations of diverse organic molecules via ROS generation and electron transfer.

Late-stage functionalization (LSF) enables the direct, site-selective modification of complex molecules and has become a key strategy in sustainable drug discovery and chemical biology. While homogeneous photocatalysis has traditionally dominated this field, recent advances in materials engineering and catalyst design have triggered a new interest in heterogeneous photocatalysis. Although classical heterogeneous photocatalysts such as metal oxides and carbon nitrides are long established, their nanoscale re-engineering and integration into LSF have only recently enabled enhanced reactivity, selectivity, and recyclability. This review surveys the recent evolution of heterogeneous photocatalytic systems, from traditional semiconductors to covalent organic frameworks and metal-organic frameworks, for selective LSF. By connecting developments in materials chemistry with photoredox catalysis, this contribution highlights the growing potential of heterogeneous photocatalysts as scalable and sustainable platforms for complex molecule synthesis.

ABSTRACT A mild photoredox‐catalyzed method for the C─N bond cleavage of aliphatic tertiary amines to construct medicinally significant α‐ketoamides has been reported. The reaction showcases the simultaneous formation of C─N and C─O bonds in a single step. In this study, the tertiary amine acts as a dual‐function reagent, serving both as a reductant and nitrogen source, thereby obviating the need for external nitrogen‐based coupling partners in the presence of phenylacetylene and catalytic thiophenol. Beyond providing an easier route to complex molecules from simple starting materials, our work highlights the hidden utility of tertiary amines in photoredox catalysis, offering a platform for late‐stage functionalization and C─N bond activation.

We report herein a transition-metal-free C(sp3)-C(sp2) cross-coupling approach to prepare branched allylamines and azaarylmethylamines. Key to the process is the enhanced reactivity of the 2-azaallyl anions generated from N-fluorenyl alkylimines. A broad range of functional groups are tolerated and the reaction proceeds under room temperature conditions without transition metals, external initiators or photoredox catalysts. Notably, no deprotonative isomerization or C3 site-selective products were observed. The synthetic utility of the present work was showcased by an efficient one-pot procedure and ketoimine hydrolysis.

Existing strategies are typically limited to modifying a C-H site (α or β-position) of saturated cyclic amines, but the asymmetric difunctionalization of vicinal C-H bonds remains a formidable challenge. To address this challenge, this work introduces a synergistic catalytic system that merges visible-light photocatalysis with asymmetric copper and chiral phosphoric acid catalysis. This system enables the enantioselective synthesis of ring-fused amine skeletons by activating vicinal C-H bonds in straightforward saturated cyclic amines. The reaction proceeds in good yields (up to 76%) and excellent enantioselectivity (up to 92% ee). This work describes detailed mechanistic studies that identify the specific dual chiral catalytic system that forms the basis for the enantioselectivity.