Harnessing the synergistic power of light and electricity: an emerging frontier in catalytic heterocycle synthesis

Abstract

The strategic integration of photochemistry and electrochemistry in organic synthesis has opened new avenues for catalytic heterocycle synthesis. This highlight provides a comprehensive overview of photoelectrocatalytic heterocycle forming strategies, discussing the mechanistic aspects and offering insights into the future prospects of this emerging field. Based on the distinct mechanistic pathways, the transformations herein have been preliminarily classified into four categories: (1) photoexcitation of electrochemically generated radical ion catalysts, (2) electrochemically mediated photoredox catalysis, (3) electrochemically mediated photoinduced ligand-to-metal charge transfer catalysis, and (4) interfacial photoelectrocatalysis and others.

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Yanchen Chen

Yanchen Chen was born in Guangdong Province, China. Since 2023, he has been an undergraduate student of Beijing Normal University at Zhuhai, majoring in chemistry. He is currently conducting research on photo- and electrochemical organic synthesis under the supervision of Dr Binbin Huang.

Binbin Huang

Binbin Huang obtained his bachelor's degree from Zhejiang University in 2014. Later, he earned both his master's degree (2016) and PhD (2021) under the supervision of Prof. Wujiong Xia from the Harbin Institute of Technology. Upon completion of his doctoral studies, he joined Beijing Normal University at Zhuhai as a faculty member. His research primarily focuses on the development of sustainable organic synthetic protocols utilizing photo- and electrochemical methods.

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1. Introduction

In the field of modern organic synthesis, chemists have never stopped exploring more environmentally benign synthetic methodologies. In this context, both organic photochemistry¹ and electrochemistry² have come into their sight, being promising alternatives to conventional thermochemistry. When a compound absorbs light energy and transitions to an excited state, significant changes occur in its electronic distribution and configuration, thereby initiating the following chemical transformations. This distinct mechanism makes photochemical reactions, especially those driven by visible-region light, particularly attractive, owing to their unique reactivity, mild conditions and high selectivity.³ In electrochemical organic transformations, traceless electrons serve as intrinsic redox agents, replacing hazardous chemical oxidants/reductants and thereby reducing both costs and waste generation. By precisely tuning the applied electric potential and introducing appropriate mediators, it is feasible to control selectivity and suppress undesirable side reactions.⁴

While the use of either light irradiation or electrical potential to achieve organic transformations has been extensively studied during the last one or two decades, the integration of both, known as photoelectrocatalysis (PEC) or electrophotocatalysis (EPC), represents a relatively recent development.⁵ The synergistic combination of light and electricity enables novel catalytic pathways, reduces the reliance on external chemical oxidants/reductants, and significantly broadens substrate compatibility, thereby improving both the versatility and sustainability of synthetic methodologies. Since 2019, an increasing number of photoelectrocatalytic systems have been introduced for achieving selective organic transformations, with particular emphasis on cross-coupling reactions (for C–B,⁶ C–C,⁷ C–N,⁸ C–O,⁹ C–P,¹⁰ and other¹¹ bond formation) and (di)functionalization of unsaturated moieties,¹² among others.¹³

Heteroatom-containing cyclic frameworks, commonly referred to as heterocycles, are widely present as key structural motifs in pharmaceuticals, natural products, and agricultural chemicals.¹⁴ Therefore, the efficient, economical, and sustainable construction of heterocycles has long been a central research focus in both academic and industrial settings. Since the traditional approaches often involve harsh reaction conditions and hazardous reagents, light-induced and electrochemically driven alternatives have emerged in recent years, providing innovative, selective, and environmentally benign methods for the synthesis of diverse heterocycles.¹⁵ However, in the more advanced field of organic photoelectrochemistry, cyclization strategies for heterocycle formation have received relatively limited attention compared to other transformation types,^6–13 and thus remain largely underdeveloped.

This highlight focuses on the current advancements made in photoelectrocatalytic heterocycle synthesis, discussing the synthetic aspects of these protocols (Scheme 1a). Typically, under concurrent light-irradiation and electrolysis, cyclization reactions involve the photoexcitation of ground-state photocatalysts (PCs) to initiate the subsequent chemical processes, with anodic oxidation for the (re)generation of key catalytic species or ground-state PCs and cathodic reduction serving as a counter reaction for hydrogen gas evolution. Based on the distinct mechanistic pathways, these transformations can be preliminarily classified into four categories (Scheme 1b): (1) photoexcitation of electrochemically generated radical ion catalysts (Scheme 1b, i), (2) electrochemically mediated photoredox catalysis (Scheme 1b, ii), (3) electrochemically mediated photoinduced ligand-to-metal charge transfer (LMCT)¹⁶ catalysis (Scheme 1b, iii), and (4) interfacial photoelectrocatalysis (i-PEC)¹⁷ and others (Scheme 1b, iv). It is worth noting that alkene epoxidation, a fundamental organic transformation used for synthesizing three-membered epoxide rings, has recently been employed as a model reaction in interfacial photoelectrochemical research studies.¹⁸ However, such studies are primarily rooted in physical chemistry and materials science, focusing on the efficient conversion of light energy into electrical energy, featuring only preliminary synthetic applications. As a consequence, these protocols are excluded from the scope of this highlight, except for those involving the formation of more complex heterocyclic structures with more significant implications for organic chemistry. By systematically examining the detailed reaction conditions, representative substrate scopes, and plausible mechanistic proposals, this highlight discusses the advantages and limitations of current methodologies, with the intention of inspiring future research in this field.

Scheme 1 Photoelectrocatalytic heterocycle synthesis: an overview of the current advances.

2. Photoexcitation of electrochemically generated radical ion catalysts

This innovative strategy primarily employs a specially designed catalytic species, termed an electrophotocatalyst, which first undergoes facile single-electron oxidation/reduction at a moderate potential to form a radical ion. Upon absorbing light of specific wavelengths, this radical ion further undergoes photoexcitation to an excited state, featuring strong oxidizing/reducing capability to facilitate the formation of the desired heterocycle. Such a strategy allows certain high-potential-demanding transformations to occur under milder potentials, thereby ensuring better functional group tolerance.

In 2019, the Lambert group developed a trisaminocyclopropenium ion (TAC⁺) electrophotocatalyst, which is prone to oxidation at the anode (E_1/2 = 1.26 V vs. SCE) to form a stable red-colored radical dication (TAC˙²⁺) for further photoexcitation (λ_max = 450, 500, and 550 nm), thereby producing a strongly oxidizing species TAC˙²⁺* (E_ox = 3.33 V vs. SCE).¹⁹ Based on this study, in 2021, they introduced an electrophotocatalytic vicinal C–H diamination or oxyamination of alkylated arenes (2-1), affording either 3,4-dihydroimidazoles (2-2) or oxazolines (2-3 or 2-4) as products with acetonitrile serving as both the solvent and nitrogen source (Scheme 2).²⁰ The reactions were carried out in a divided cell under controlled potential, irradiated with a white compact fluorescent lamp (CFL), in the presence of 8 mol% TAC catalyst and trifluoroacetic acid (TFA) as a co-solvent. Notably, changing the electrolyte would significantly influence product selectivity: Et₄NBF₄ favored the formation of 3,4-dihydroimidazoles (2-2), whereas LiClO₄ favored oxazolines (2-3 or 2-4). Mechanistically, TAC-facilitated electrophotocatalytic oxidation and deprotonation events generate the benzylic cation Int2-B. This intermediate is proposed to undergo a Ritter-type reaction followed by acid-catalyzed elimination, yielding α-methylstyrene Int2-D. Subsequent single-electron oxidation of Int2-D, followed by trapping with acetonitrile and further oxidation, leads to the formation of the dicationic intermediate Int2-G or Int2-J. These intermediates then undergo another Ritter-type transformation and nucleophilic cyclization to yield either dihydroimidazole 2-2 or oxazoline (2-3 or 2-4) as the product.

Scheme 2 Electrophotocatalytic diamination and oxyamination of vicinal C–H bonds for the synthesis of N-heterocycles.

In the following year, the same research group further demonstrated a regiodivergent electrophotocatalytic aminooxygenation of aryl olefins (3-1) for the synthesis of oxazoline derivatives (3-2 or 3-4) using either water or urethane (3-3) as the inexpensive nucleophilic reagent (Scheme 3).²¹ A similar TAC-based system was used, generating the radical cation intermediate Int3-A from 3-1 under photoelectrochemical conditions. This intermediate is readily attacked by either the O- or N-centered nucleophile, followed by electrophotocatalytic oxidation, yielding the corresponding benzylic cation Int3-C or Int3-F, respectively. Intramolecular polar cyclization of Int3-F affords the 2,1-aminooxygenation product (3-4), whereas intermolecular attack by the solvent MeCN on Int3-C, in competition with water, leads to the formation of Int3-D, which subsequently cyclizes to yield the 1,2-aminooxygenation product (3-2). The mild reaction conditions enable broad functional group tolerance, including compatibility with various heterocycles and complex molecular architectures. Furthermore, the protocol exhibits favorable syn-diastereoselectivity and demonstrates promising applicability.

Scheme 3 Regiodivergent electrophotocatalytic aminooxygenation of aryl olefins.

In addition to these oxidative annulation strategies from Lambert's group, it is noteworthy that one of Wickens’ works also included a reductive cyclization of an alkene-tethered aryl chloride.^10b The cyclization proceeds through the capture of an aryl radical, generated via the reductive cleavage of the C_Ar–Cl bond by NpMI˙⁻*, an excited-state fused organic species formed through a sequential cathodic reduction and photoexcitation process, ultimately leading to the formation of a dihydrobenzofuran framework.

3. Electrochemically mediated photoredox catalysis

This paradigm utilizes the classical photoredox catalysis, in which the photoexcited photocatalyst undergoes processes such as single-electron transfer (SET), energy transfer (EnT), and hydrogen atom transfer (HAT)²² to generate radical-type intermediates that participate in the following cyclization reactions. The regeneration of the ground-state photocatalyst is usually achieved through anodic oxidation, thereby eliminating the requirement for an external chemical oxidant. Meanwhile, cathodic evolution of environmentally benign molecular hydrogen serves as the counter reaction. This approach provides a more sustainable alternative to conventional photochemical reactions.

The incorporation of silyl groups into organic molecules through photo- or electrochemical methods has attracted significant research focus over the past few decades.²³ In 2023, the research group led by Wang and Hou disclosed an organo-photoelectrochemical approach for silylative cyclization of CF₃-substituted N-arylacrylamides (4-1) with organosilanes (4-2), employing 9,10-phenanthrenequinone (PQ) as a photocatalyst (Scheme 4a).²⁴ Under the irradiation at 420–425 nm, PQ is excited to a diradical state (PQ*), which demonstrates strong HAT capability. This enables the abstraction of a hydrogen atom from silane 4-2, generating a silyl radical intermediate (Int4-A) and PQH˙. Subsequent radical addition of Int4-A to substrate 4-1, followed by intramolecular cyclization, leads to the formation of the radical intermediate Int4-C. Finally, the silylated 3-CF₃-2-oxindole product (4-3) is afforded through a second HAT reaction between Int4-C and PQH˙, concomitantly regenerating the reduced photocatalyst PQH₂. In this system, electro-oxidation facilitates the regeneration of ground-state PQ, while proton reduction at the cathode obviates the need for external chemical oxidants. Later that year, the same group further applied this photoelectrocatalytic system to generate acyl radicals from formamides or aldehydes (4-5) (Scheme 4b).²⁵ A wide range of acylated 3-CF₃-2-oxindoles (4-6) were synthesized from CF₃-substituted N-arylacrylamides (4-4) through a similar tandem radical cyclization pathway.

Scheme 4 Organo-photoelectrocatalytic protocols for the synthesis of 3-CF₃-2-oxindoles.

Synthetic methods for the efficient incorporation of fluoroalkyl groups, such as –CF₃ and –CF₂H, are of significant interest in medicinal chemistry.²⁶ Employing N-heterocycle-tethered alkenes (5-1) as cyclization precursors, the team led by Liang and Shi developed a tri- or difluoromethylative cyclization with fluoromethanesulfinate salts (5-2), using Eosin Y as a photocatalyst under photoelectrochemical conditions (Scheme 5).²⁷ Notably, both activated and unactivated terminal alkenes were proven as competent substrates, enabling the synthesis of a broad range of fused N-heterocyclic compounds (5-3) through an electrochemically mediated photoredox catalytic cycle in which the excited-state photocatalyst (EY*) functioned as a mild single-electron oxidant. Moreover, this methodology was also demonstrated to be applicable to the synthesis of various other fluoroalkylated nitrogen-containing heterocycles, including compounds 5-5.

Scheme 5 Photoelectrocatalytic tri- or difluoromethylative cyclization of alkenes.

Given the significance of heterocycles containing sulfur- and selenium-based substituents,²⁸ in 2024 and 2025, Liang and colleagues sequentially developed three photoelectrocatalytic strategies for the construction of 4-pyrrolin-2-one frameworks with simultaneous incorporation of thiocyanate,²⁹ aryl/alkylselenyl,³⁰ and alkyl sulfonyl³¹ groups. By means of self- or acridinium-photoelectrocatalysis, Sun, Liang, and their coworkers achieved an external-oxidant-free thiocyanocyclization of various activated alkenes, yielding a broad array of thiocyanated heterocycles (Scheme 6a).²⁹ Interestingly, in this system, the acridinium salt, substrates 6-1, and products 6-3 are all capable of undergoing photoexcitation, followed by single-electron reduction by KSCN (6-2), thereby generating the key radical species ˙SCN to initiate cyclization. In the same year, the team led by Liang, Sun, and Shi reported a selenocyclization via three hybrid (photo)electrochemical protocols, using diorganyl diselenides (6-5) as the selenyl sources (Scheme 6b).³⁰ Under 4CzIPN-photoelectrocatalysis (method A), PC-free photoelectrochemical conditions (method B), or NHPI-mediated electrochemical conditions (method C), the selenocyclization could be realized through both radical-based (Int6-D) and cation-based (Int6-F) pathways.

Scheme 6 Photoelectrocatalytic cyclization of 3-aza-1,5-dienes for the construction of 4-pyrrolin-2-one skeletons.

To date, various sulfur dioxide surrogates have emerged as versatile and sustainable alternatives to the troublesome gaseous SO₂ for the synthesis of SO₂-containing compounds, among which the 1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide) adduct (DABSO) has received particular attention.³² In 2025, the research group of Li and Liang developed a three-component net-oxidative sulfonylation of 3-aza-1,5-dienes (7-1) with DABSO (7-2) and organotrifluoroborates (7-3) through photoelectrocatalysis (Scheme 7a).³¹ Mechanistic investigations revealed that DABSO undergoes in situ conversion to 1,4-diazabicyclo[2.2.2]octane (DABCO) after donation of SO₂, which acts as an electron shuttle between the acridine-based photoelectrocatalytic cycle and 7-3, thereby facilitating the oxidative generation of the alkyl radical intermediate Int7-A for triggering cyclization.

Scheme 7 Photoelectrochemical cyclization for the synthesis of N-heterocycles with sulfur-substituent introduction.

In line with their previous studies,^29–31 in 2025, Liang, Sun, Shi, and colleagues disclosed a photoelectrochemical cyclization of nitrogen-containing unactivated alkenes, including pyrazole-derived ones (7-5), for the construction of various N-heterocycles bearing sulfur-containing substituents, employing 2,4,6-triphenylpyrylium tetrafluoroborate (TPPT) as the organic photocatalyst (Scheme 7b).³³ In this work, NaSCN (7-6) and NaSSO₂R (7-7) served as the sources of ˙CN and ˙SO₂R, respectively, enabling the formation of various heterocyclic frameworks such as 5,6-dihydropyrazolo[5,1-a]isoquinoline derivatives (7-8 and 7-9).

Selective activation of C(sp³)–H bonds for direct functionalization has emerged as a prominent focus in both organic photo- and electrochemical synthesis.³⁴ In 2024, the research team led by Liang, Chang, and Shi introduced a hybrid system integrating electrolysis, photocatalysis, and a Brønsted base to synthesize polycyclic pyrimidin-4-ones (8-3) through dehydrogenative carbocyclization of unactivated alkenes (8-1) with simple malonates (8-2) (Scheme 8).³⁵ The proposed mechanism involves a base-mediated proton-coupled electron transfer (PCET)³⁶ process, which plays a pivotal role in the generation of the carbon-centered radical Int8-A from 8-2. Subsequent addition of Int8-A to the alkene moiety of 8-1 produces the radical Int8-B, which further cyclizes to form the heterocyclic scaffold (Int8-C). This intermediate can either undergo anodic oxidation followed by deprotonation to yield the final product 8-3 or proceed via a photoredox-mediated reduction and protonation pathway to afford Int8-E, which subsequently undergoes anodic dehydrogenation to produce 8-3. The authors proposed that the synergistic interaction between light and electricity arises from the rapid anchoring of Int8-C by the oxidative quenching photoredox cycle of fac-Ir(ppy)₃ at the cathode.

Scheme 8 Photoelectrochemical synthesis of polycyclic pyrimidin-4-ones from unactivated alkenes and malonates.

Alkynes have been utilized as versatile moieties for achieving cyclization transformations to access heterocyclic compounds.³⁷ In 2024, the Ackermann group reported a [4 + 2] annulation between benzothioamides (9-1) and alkynes (9-2) for the synthesis of functionalized isothiochromenes (9-3), enabled by a photoelectrochemical PCET strategy (Scheme 9).³⁸ Detailed spectroscopic studies and control experiments revealed that the hydrogen bonding interaction between the strong N–H of 9-1 and the base K₂CO₃, coupled with photoelectrocatalytic electron transfer, promotes the formation of the nitrogen radical Int9-A, which rapidly isomerizes into the sulfur radical Int9-B. The subsequent radical oxidative annulation with alkyne 9-2 delivers the six-membered S-heterocycle product 9-3. This work represents a breakthrough in photoelectrocatalytic mono-sulfur-containing heterocycle synthesis.

Scheme 9 Photoelectrochemical [4 + 2] annulation for S-heterocycle synthesis.

The in situ formed electron donor–acceptor (EDA) complexes have been strategically exploited to promote various visible-light induced organic transformations.³⁹ In 2024, Roy and colleagues combined EDA complex formation with photoelectrochemical conditions to catalyze intramolecular C–S bond formation for the synthesis of diverse sulfur-containing heterocycles, including benzo[d]thiazoles (10-2), using a phenalenyl-based photocatalyst (PL-Cat.) developed by their research group (Scheme 10).⁴⁰ Mechanistically, PL-Cat. engages in a noncovalent interaction with substrate 10-1 through ion pair–π interactions to generate an EDA complex (Int10-A), as evidenced by mechanistic investigations involving UV-visible spectroscopic analysis, cyclic voltammetry experiments, and computational calculations (path a). Upon visible-light irradiation, complex Int10-A is excited to form Int10-A*, which subsequently undergoes intramolecular SET to yield a contact ion pair (Int10-B), which then collapses into PC˙⁻ and the radical cation Int10-C. This radical cation is deprotonated by HO⁻ generated at the cathode, resulting in the formation of an S-centered radical (Int10-D). Further anodic oxidation and deprotonation of Int10-D led to the final aromatic N-,S-heterocycle 10-2. Alternatively, direct excitation of the PC followed by reductive quenching with 10-1 to generate Int10-C and PC˙⁻ may also be a plausible pathway (path b). The ground-state PC can be efficiently regenerated via anodic oxidation of PC˙⁻, thereby closing the catalytic cycle.

Scheme 10 Photoelectrocatalytic intramolecular C–S bond formation using a phenalenyl-based photocatalyst.

4. Electrochemically mediated photoinduced LMCT catalysis

The rapidly emerging photoinduced LMCT catalysis has also been successfully integrated into photoelectrochemical systems, offering more sustainable strategies for organic synthesis, including heterocycle formation.^16c This photocatalytic mode begins with the coordination of a nucleophilic ligand to an electron-deficient metal center, forming a metal–ligand complex. Upon photoexcitation, the coordinate bond undergoes homolytic cleavage, yielding a reduced metal center and an oxidized, ligand-centered radical. In contrast to the well-developed photoredox catalysis, the primary conceptual advantage of LMCT lies in its ability to readily generate highly reactive radical species (such as Cl˙, Br˙, and RO˙)⁴¹ upon irradiation at specific wavelengths, without the necessity for precise redox potential matching. Similar to the strategies outlined in the previous section, electrochemical oxidation is utilized as an alternative to costly and hazardous chemical oxidants for regenerating high-valent metal catalysts, with the cathodic reduction of protons serving as a benign counter reaction.

During the period from 2022 to 2024, the group of Zeng and Xu sequentially disclosed three electrophotochemical LMCT protocols for the construction of diverse benzimidazo-fused isoquinolinones, using cerium trichloride (or its hydrate) as a cost-effective photocatalyst.^42–44 In 2022, they first applied this strategy to achieve selective activation of Si–H bonds, which is governed by polarity-matching effects, generating silyl radicals that initiate cyclization and ultimately yield Si-functionalized benzimidazo-fused isoquinolinones (11-3) (Scheme 11a).⁴² The efficient formation of reactive MeO˙ (or [Cl − OHCH₃]˙) is accomplished through the homolytic cleavage of the excited-state complex Int11-A, which subsequently acts as an electrophilic HAT agent to selectively activate more hydridic Si–H bonds rather than C–H bonds, thereby producing the silyl radical Int11-B. In the following year, their group further extended this electrophotochemical Ce-LMCT catalytic system to direct alkane C–H activation, enabling the synthesis of a broad range of alkyl-substituted benzimidazo-fused isoquinolinones (11-6) (Scheme 11b).⁴³ Compared to earlier approaches that rely on prefunctionalized Si- or C-centered radical precursors, these photoelectrocatalytic methodologies offer significant advantages in terms of both atom efficiency and step economy, and do not require the use of external chemical oxidants.

Scheme 11 Electrophotochemical Ce-LMCT catalyzed Si–H and C–H activation for N-heterocycle synthesis.

Decarboxylative functionalization of bench-stable, readily available, and cost-effective carboxylic acids has attracted considerable interest among researchers in the fields of organic photo- and electrochemistry.⁴⁵ To address the limitations in substrate compatibility and chemoselectivity identified in their prior work,⁴³ in 2024, Zeng, Xu, and coworkers used a range of primary, secondary, and tertiary aliphatic carboxylic acids (12-2) as alkyl radical precursors, successfully achieving decarboxylative carbocyclization through electrophotochemical Ce-LMCT catalysis (Scheme 12).⁴⁴ Mechanistically, the Ce(IV) species generated at the anode coordinates with carboxylic acid 12-2, forming a complex which upon irradiation at 390 nm transitions to an excited state (Int12-A). This excited complex subsequently undergoes homolytic cleavage, yielding reduced Ce(III) and an acyloxy radical intermediate (Int12-B), which proceeds to participate in the following decarboxylative cyclization process, finally delivering the alkylated benzimidazo-fused isoquinolinone (12-3).

Scheme 12 Electrophotochemical Ce-LMCT catalyzed decarboxylative cyclization.

Apart from carbon and silicon, their congener germanium has also garnered increasing interest within the synthetic chemistry community due to its distinctive properties when integrated into molecular architectures.⁴⁶ In 2023, Ackermann's group employed photoinduced Fe-LMCT catalysis to activate Si–H and Ge–H bonds of hydrosilanes and hydrogermanes (13-2), thereby enabling radical cyclization of α,β-unsaturated amides (13-1) to selectively furnish a range of silyl- or germyl-substituted indolin-2-ones (13-3) under photoelectrochemical conditions (Scheme 13).⁴⁷ The photoinduced LMCT process in the excited iron(III)–Cl complex (Int13-A) facilitated the generation of the chlorine radical (Cl˙), followed by a crucial HAT event to yield a HCl molecule. This sequence enabled selective activation of Si–H and Ge–H bonds through a radical-polarity-matched mechanism, effectively overcoming the challenge posed by the similar redox potentials of Si/Ge–H and C–H bonds.

Scheme 13 Photoelectrochemical Si–H and Ge–H activation for indolin-2-one synthesis.

5. Interfacial photoelectrocatalysis and others

Reactions proceeding through mechanisms distinct from the aforementioned types have been summarized in this section.

Intramolecular 1,n-HAT has been strategically applied in organic synthesis for the precise activation of specific remote C(sp³)–H bonds.⁴⁸ As an early endeavor in constructing heterocyclic frameworks through the synergistic use of photo- and electrochemical catalysis, in 2019, Stahl's group developed a dehydrogenative C(sp³)–H/N–H coupling protocol, enabling the efficient synthesis of a broad scope of pyrrolidines (14-2) and oxazolines (14-4) (Scheme 14).⁴⁹ As a variant of the classical Hofmann–Löffler–Freytag (HLF) reaction, this protocol employed iodide as an electrochemical mediator, the regeneration of which (0.3–0.7 V vs. Fc/Fc⁺) substantially reduced the required electrochemical potential, thereby overcoming the limited functional group tolerance observed in earlier studies. Mechanistically, electrochemical oxidation of iodide generates molecular iodine, which subsequently reacts with the sulfonamide substrate 14-1 to form an N–I intermediate (Int14-A). Upon visible-light irradiation, the N–I bond of Int14-A undergoes homolytic cleavage, yielding a nitrogen-centered radical (Int14-B), which readily undergoes intramolecular 1,5-HAT to generate a remote carbon-centered radical (Int14-C). This radical is then intercepted by iodine to form an alkyl iodide intermediate (Int14-D), which undergoes Brønsted base-promoted nucleophilic displacement by the pendant nitrogen nucleophile, ultimately furnishing the pyrrolidine product 14-2. Compared to other electrochemical C–H amination reactions, this strategy exhibited significantly enhanced functional group tolerance, as exemplified by its ability to accommodate electron-rich aromatic moieties that typically engage in undesirable side reactions under high-potential conditions.

Scheme 14 Photoelectrochemical synthesis of pyrrolidines and oxazolines through intramolecular dehydrogenative coupling.

In recent years, interfacial photoelectrochemistry has garnered increasing attention as a promising approach for organic synthesis, offering significant advantages such as cost-effectiveness, reusability and stability of photoelectrodes as heterogeneous catalysts.¹⁷ In 2022, the research group led by Wu, Kim, and Kim reported a self-biasing interfacial photoelectrocatalytic strategy for the cascade C–H activation/cyclization of N-aryl tetrahydroisoquinolines (15-1) with malononitrile derivatives (15-2), enabling the construction of nitrogen-containing fused cyclic compounds (15-3), using an m-BiVO₄ film as the photoanode (Scheme 15).⁵⁰ Under visible-light irradiation, the photoanode is excited, generating high-energy electron–hole pairs that facilitate the oxidation of substrates and intermediates without the need for an external bias and with a minimal overpotential. According to the proposed mechanism, the key intermediate Int15-F may form either through radical–radical cross-coupling between Int15-B and Int15-E or via a nucleophilic attack of Int15-D on Int15-C. Subsequent oxidation–deprotonation of Int15-F yields the radical intermediate Int15-G, which undergoes radical cyclization followed by further oxidation–deprotonation to afford the target fused N-heterocyclic compound 15-3. Notably, the photoanode in this work can be readily recovered after cleaning with dichloromethane and reused for more than ten cycles while retaining comparable catalytic activity, a clear advantage over homogeneous photoelectrochemical methods.

Scheme 15 Unbiased photoelectrocatalyzed synthesis of N-bearing fused rings.

In 2024, Shi, Li, and their colleagues described a photoelectrochemical dehydrogenative cyclization of 2-arylbenzoic acids and 2-arylbenzamides (16-1) in a PEC cell, employing a mesoporous WO₃ photoanode in combination with a platinum cathode (Scheme 16).⁵¹ The reaction is initiated by TMG (tetramethylguanidine)-mediated deprotonation of 16-1, followed by single-electron oxidation mediated by the photo-excited photoanode, leading to the formation of the O- or N-centered radical intermediate Int16-A. This radical undergoes intramolecular capture by the adjacent aryl group to form a six-membered ring (Int16-B), which subsequently undergoes oxidation–deprotonation to yield the corresponding lactone or lactam product 16-2.

Scheme 16 Photoelectrochemical dehydrogenative cyclization of 2-arylbenzoic acids and 2-arylbenzamides.

Very recently, the research team led by Kim et al. disclosed a catalyst-free photon-primed organic electrosynthetic strategy for the efficient synthesis of various substituted oxazoles (17-4) and fused furans/pyrroles (17-6) (Scheme 17).⁵² Mechanistically, the quinone substrate 17-1 is readily excited to its triplet state (17-1*) upon visible-light irradiation, which initiates a subsequent photocycloaddition with alkyne 17-2, generating a highly reactive p-quinone methide intermediate (Int17-A). This species undergoes facile anodic oxidation to form a highly electrophilic radical cation Int17-B, capable of reacting with weak nucleophiles such as 17-3 (also phenols/anilines 17-5). The resulting intermediate Int17-C subsequently undergoes polar cyclization, a 1,2-aryl shift, and deprotonation to yield Int17-F, which then engages in an SET process with Int17-A, producing the final product 17-4 and regenerating Int17-B. Such a redox-chain mechanism significantly enhances the overall efficiency of the transformation, leading to an apparent faradaic efficiency exceeding 100%. A broad substrate scope was demonstrated, including the late-stage modification of bioactive scaffolds, thereby highlighting the synthetic utility and potential of this photoelectrocatalytic methodology.

Scheme 17 Photon-primed organic electrosynthesis of oxazoles and fused furans/pyrroles.

6. Summary and outlook

Over the past few years, the rapidly emerging field of organic photoelectrocatalysis has demonstrated preliminary applications in novel and sustainable heterocycle synthesis. These promising approaches not only expand the synthetic toolbox, but also inspire the innovative design of new cyclization paradigms.

Despite the notable advances, significant challenges and opportunities remain to be addressed. First, the majority of current studies have focused on the synthesis of nitrogen-containing heterocycles, featuring rather limited structural diversity, with considerably fewer reports on the construction of other heterocycles, such as those containing oxygen and sulfur, among others. Second, the existing reactions usually exhibit stringent structural requirements for radical addition, thereby limiting their practical applicability in the synthesis of complex molecules. Furthermore, current strategies have predominantly focused on the synthesis of saturated or partially saturated heterocycles, with limited progress in the construction of aromatic ones.

In conclusion, the rapid emergence of organic photoelectrocatalysis has led to the establishment of diverse innovative cyclization strategies for heterocycle synthesis. It is anticipated that continued efforts from the synthetic community will focus on the development of more efficient and sustainable methodologies for constructing a wider variety of heterocyclic frameworks from readily available starting materials.

Conflicts of interest

There are no conflicts to declare.

Data availability

No primary research results, software or code have been included and no new data were generated or analysed as part of this review.

Acknowledgements

The authors are grateful for the financial support from Beijing Normal University (No. 310432105).

References

1. Selected reviews: (a) N. Hoffmann, Photochemical Reactions as Key Steps in Organic Synthesis, Chem. Rev., 2008, 108, 1052–1103; (b) J. M. R. Narayanam and C. R. J. Stephenson, Visible light photoredox catalysis: applications in organic synthesis, Chem. Soc. Rev., 2011, 40, 102–113; (c) C. K. Prier, D. A. Rankic and D. W. C. MacMillan, Visible Light Photoredox Catalysis with Transition Metal Complexes: Applications in Organic Synthesis, Chem. Rev., 2013, 113, 5322–5363; (d) D. M. Schultz and T. P. Yoon, Solar Synthesis: Prospects in Visible Light Photocatalysis, Science, 2014, 343, 1239176; (e) N. A. Romero and D. A. Nicewicz, Organic Photoredox Catalysis, Chem. Rev., 2016, 116, 10075–10166; (f) L. Marzo, S. K. Pagire, O. Reiser and B. König, Visible-Light Photocatalysis: Does It Make a Difference in Organic Synthesis?, Angew. Chem., Int. Ed., 2018, 57, 10034–10072.
2. Selected reviews: (a) J. B. Sperry and D. L. Wright, The application of cathodic reductions and anodic oxidations in the synthesis of complex molecules, Chem. Soc. Rev., 2006, 35, 605–621; (b) J.-I. Yoshida, K. Kataoka, R. Horcajada and A. Nagaki, Modern Strategies in Electroorganic Synthesis, Chem. Rev., 2008, 108, 2265–2299; (c) B. A. Frontana-Uribe, R. D. Little, J. G. Ibanez, A. Palmad and R. Vasquez-Medrano, Organic electrosynthesis: a promising green methodology in organic chemistry, Green Chem., 2010, 12, 2099–2119; (d) R. Francke and R. D. Little, Redox catalysis in organic electrosynthesis: basic principles and recent developments, Chem. Soc. Rev., 2014, 43, 2492–2521; (e) M. Yan, Y. Kawamata and P. S. Baran, Synthetic Organic Electrochemical Methods Since 2000: On the Verge of a Renaissance, Chem. Rev., 2017, 117, 13230–13319; (f) S. Möhle, M. Zirbes, E. Rodrigo, T. Gieshoff, A. Wiebe and S. R. Waldvogel, Modern Electrochemical Aspects for the Synthesis of Value-Added Organic Products, Angew. Chem., Int. Ed., 2018, 57, 6018–6041.
3. Selected reviews: (a) J. Twilton, C. Le, P. Zhang, M. H. Shaw, R. W. Evans and D. W. C. MacMillan, The merger of transition metal and photocatalysis, Nat. Rev. Chem., 2017, 1, 0052; (b) F. Strieth-Kalthoff, M. J. James, M. Teders, L. Pitzer and F. Glorius, Energy transfer catalysis mediated by visible light: principles, applications, directions, Chem. Soc. Rev., 2018, 47, 7190–7202; (c) X.-Y. Yu, J.-R. Chen and W.-J. Xiao, Visible Light-Driven Radical-Mediated C–C Bond Cleavage/Functionalization in Organic Synthesis, Chem. Rev., 2021, 121, 506–561; (d) L. Capaldo, D. Ravelli and M. Fagnoni, Direct Photocatalyzed Hydrogen Atom Transfer (HAT) for Aliphatic C–H Bonds Elaboration, Chem. Rev., 2022, 122, 1875–1924; (e) L. Buglioni, F. Raymenants, A. Slattery, S. D. A. Zondag and T. Noël, Technological Innovations in Photochemistry for Organic Synthesis: Flow Chemistry, High-Throughput Experimentation, Scale-up, and Photoelectrochemistry, Chem. Rev., 2022, 122, 2752–2906; (f) G. Li, T. Li, L. Luo, Y. Tan and Z. Lu, Photo and earth-abundant metal dual catalysis in organic synthesis, Org. Chem. Front., 2025, 12, 4530–4607.
4. Selected reviews: (a) S. Tang, Y. Liu and A. Lei, Electrochemical Oxidative Cross-coupling with Hydrogen Evolution: A Green and Sustainable Way for Bond Formation, Chem, 2018, 4, 27–45; (b) C. Ma, P. Fang, Z.-R. Liu, S.-S. Xu, K. Xu, X. Cheng, A. Lei, H.-C. Xu, C. Zeng and T.-S. Mei, Recent advances in organic electrosynthesis employing transition metal complexes as electrocatalysts, Sci. Bull., 2021, 66, 2412–2429; (c) B. Huang, Z. Sun and G. Sun, Recent progress in cathodic reduction-enabled organic electrosynthesis: Trends, challenges, and opportunities, eScience, 2022, 2, 243–277; (d) J. Rein, S. B. Zacate, K. Mao and S. Lin, A tutorial on asymmetric electrocatalysis, Chem. Soc. Rev., 2023, 52, 8106–8125; (e) Z. Tan, H. Zhang, K. Xu and C. Zeng, Electrochemical radical-polar crossover: a radical approach to polar chemistry, Sci. China: Chem., 2024, 67, 450–470; (f) W. Zeng, Y. Wang, C. Peng and Y. Qiu, Organo-mediator enabled electrochemical transformations, Chem. Soc. Rev., 2025, 54, 4468–4501.
5. Selected reviews on photoelectrocatalytic organic synthesis: (a) Y. Yu, P. Guo, J.-S. Zhong, Y. Yuan and K.-Y. Ye, Merging photochemistry with electrochemistry in organic synthesis, Org. Chem. Front., 2020, 7, 131–135; (b) S. Wu, J. Kaur, T. A. Karl, X. Tian and J. P. Barham, Synthetic Molecular Photoelectrochemistry: New Frontiers in Synthetic Applications, Mechanistic Insights and Scalability, Angew. Chem., Int. Ed., 2022, 61, e202107811; (c) L. Qian and M. Shi, Contemporary photoelectrochemical strategies and reactions in organic synthesis, Chem. Commun., 2023, 59, 3487–3506; (d) F. Medici, V. Chiroli, L. Raimondi and M. Benaglia, Latest updates in ElectroPhotoChemical reactions, Tetrahedron Chem, 2024, 9, 100061; (e) Z. Ye, H. Liu and F. Zhang, Recent Advances in Organic Electrophotocatalytic Synthesis, Chin. J. Org. Chem., 2024, 44, 840–870; (f) Z. Shen, J.-L. Tu and B. Huang, Unleashing the potentiality of metals: synergistic catalysis with light and electricity, Org. Chem. Front., 2024, 11, 4024–4040; (g) M. C. Lamb, K. A. Steiniger, L. K. Trigoura, J. Wu, G. Kundu, H. Huang and T. H. Lambert, Electrophotocatalysis for Organic Synthesis, Chem. Rev., 2024, 124, 12264–12304; (h) C. Huang, P. Xiong, X.-L. Lai and H.-C. Xu, Photoelectrochemical asymmetric catalysis, Nat. Catal., 2024, 7, 1250–1254; (i) P. Xiong and H.-C. Xu, Molecular Photoelectrocatalysis for Radical Reactions, Acc. Chem. Res., 2025, 58, 299–311.
6. Selected reports on photoelectrocatalytic C–B cross-coupling: (a) H. Kim, H. Kim, T. H. Lambert and S. Lin, Reductive Electrophotocatalysis: Merging Electricity and Light To Achieve Extreme Reduction Potentials, J. Am. Chem. Soc., 2020, 142, 2087–2092; (b) P.-F. Zhong, J.-L. Tu, Y. Zhao, N. Zhong, C. Yang, L. Guo and W. Xia, Photoelectrochemical oxidative C(sp³)–H borylation of unactivated hydrocarbons, Nat. Commun., 2023, 14, 6530; (c) Y. Cao, C. Huang and Q. Lu, Photoelectrochemically driven iron-catalysed C(sp³)−H borylation of alkanes, Nat. Synth., 2024, 3, 537–544; (d) W. Wei, B. Wang, S. L. Homölle, J. Zhu, Y. Li, T. von Münchow, I. Maksso and L. Ackermann, Photoelectrochemical Iron-Catalyzed C(sp³)–H Borylation of Alkanes in a Position-Selective Manner, CCS Chem., 2024, 6, 1430–1438; (e) J. Ling, A. L. V. Haar, K. Z. Colley, J. Kim, A. J. Musser and P. J. Milner, Polymer connectivity governs electrophotocatalytic activity in the solid state, Nat. Chem., 2025 DOI:10.1038/s41557-025-01897-7; (f) L. Song, J.-L. Zhuang, P. Xiong and H.-C. Xu, Photoelectrocatalytic Heteroarene C(sp²)-H Borylation, Green Chem., 2025 10.1039/D5GC03231H.
7. Selected reports on photoelectrocatalytic C–C cross-coupling: (a) H. Yan, Z.-W. Hou and H.-C. Xu, Photoelectrochemical C-H Alkylation of Heteroarenes with Organotrifluoroborates, Angew. Chem., Int. Ed., 2019, 58, 4592–4595; (b) P. Xu, P.-Y. Chen and H.-C. Xu, Scalable Photoelectrochemical Dehydrogenative Cross-Coupling of Heteroarenes with Aliphatic C-H Bonds, Angew. Chem., Int. Ed., 2020, 59, 14275–14280; (c) C.-Y. Cai, X.-L. Lai, Y. Wang, H.-H. Hu, J. Song, Y. Yang, C. Wang and H.-C. Xu, Photoelectrochemical asymmetric catalysis enables site- and enantioselective cyanation of benzylic C–H bonds, Nat. Catal., 2022, 5, 943–951; (d) Y.-J. Chen, W.-H. Deng, J.-D. Guo, R.-N. Ci, C. Zhou, B. Chen, X.-B. Li, X.-N. Guo, R.-Z. Liao, C.-H. Tung and L.-Z. Wu, Transition-Metal-Free, Site-Selective C–F Arylation of Polyfluoroarenes via Electrophotocatalysis, J. Am. Chem. Soc., 2022, 144, 17261–17268; (e) W. Fan, X. Zhao, Y. Deng, P. Chen, F. Wang and G. Liu, Electrophotocatalytic Decoupled Radical Relay Enables Highly Efficient and Enantioselective Benzylic C–H Functionalization, J. Am. Chem. Soc., 2022, 144, 21674–21682; (f) L. Zou, X. Wang, S. Xiang, W. Zheng and Q. Lu, Paired Oxidative and Reductive Catalysis: Breaking the Potential Barrier of Electrochemical C(sp³)-H Alkenylation, Angew. Chem., Int. Ed., 2023, 62, e202301026; (g) J. Lu, Y. Yao, L. Li and N. Fu, Dual Transition Metal Electrocatalysis: Direct Decarboxylative Alkenylation of Aliphatic Carboxylic Acids, J. Am. Chem. Soc., 2023, 145, 26774–26782; (h) Y. Chen, Y. He, Y. Gao, J. Xue, W. Qu, J. Xuan and Y. Mo, Scalable decarboxylative trifluoromethylation by ion-shielding heterogeneous photoelectrocatalysis, Science, 2024, 384, 670–676; (i) Y. Wu, X. Wang, Z. Wang and C. Chen, Redox-neutral decarboxylative coupling of fluoroalkyl carboxylic acids via dual metal photoelectrocatalysis, Chem. Sci., 2024, 15, 18497–18503; (j) J.-L. Tu, A.-M. Hu, C. Yang, L. Guo and W. Xia, Photoelectrochemical iron–cobalt synergistic catalysis for C(sp³)–H alkenylation, Org. Chem. Front., 2025, 12, 2732–2738; (k) X. Zhou, P.-F. Zhong, Z. Li, P. Hu, J. Tu, C. Yang, L. Guo, W. Xia and T. Chen, Photoelectrochemical Iron–Nickel Synergistic Catalysis for C(sp³)-H and Dehydroxymethylative Acylation, Org. Lett., 2025, 27, 6995–7000; (l) V. Motornov, S. Trienes, S. Resta, J. C. A. Oliveira, Z. Lin, Z. Liu, T. von Münchow, C. Stückl and L. Ackermann, Photoelectrochemical Iron(III) Catalysis for Late-Stage C–H Fluoroalkylations, Angew. Chem., Int. Ed., 2025, 64, e202504143; (m) Z. Yang, S. Xu, H. Du, J. Li, T. Peng and C. Liu, Electrophotochemical Radical Relay for Remote Alkenylation of Unactivated C(sp³)–H Sites in Alcohols, Angew. Chem., Int. Ed., 2025, 64, e202508960.
8. Selected reports on photoelectrocatalytic C–N cross-coupling: (a) L. Niu, C. Jiang, Y. Liang, D. Liu, F. Bu, R. Shi, H. Chen, A. D. Chowdhury and A. Lei, Manganese-Catalyzed Oxidative Azidation of C(sp³)–H Bonds under Electrophotocatalytic Conditions, J. Am. Chem. Soc., 2020, 142, 17693–17702; (b) T. Shen and T. H. Lambert, C–H Amination via Electrophotocatalytic Ritter-type Reaction, J. Am. Chem. Soc., 2021, 143, 8597–8602; (c) S. Wu, J. Žurauskas, M. Domański, P. S. Hitzfeld, V. Butera, D. J. Scott, J. Rehbein, A. Kumar, E. Thyrhaug, J. Hauer and J. P. Barham, Hole-mediated photoredox catalysis: tris(p-substituted)biarylaminium radical cations as tunable, precomplexing and potent photooxidants, Org. Chem. Front., 2021, 8, 1132–1142; (d) Y. Wang, L. Li and N. Fu, Electrophotochemical Decarboxylative Azidation of Aliphatic Carboxylic Acids, ACS Catal., 2022, 12, 10661–10667; (e) J. Žurauskas, S. Boháčová, S. Wu, V. Butera, S. Schmid, M. Domański, T. Slanina and J. P. Barham, Electron-Poor Acridones and Acridiniums as Super Photooxidants in Molecular Photoelectrochemistry by Unusual Mechanisms, Angew. Chem., Int. Ed., 2023, 62, e202307550; (f) D. I. Ioannou, L. Capaldo, J. Sanramat, J. N. H. Reek and T. Noël, Accelerated Electrophotocatalytic C(sp³)-H Heteroarylation Enabled by an Efficient Continuous-Flow Reactor, Angew. Chem., Int. Ed., 2023, 62, e202315881; (g) Z.-W. Hou, H. Yan, J. Song and H.-C. Xu, Photoelectrocatalytic C–H amination of arenes, Green Chem., 2023, 25, 7959–7962; (h) D. I. Ioannou, E. Bombonato, J. Sanramat, J. N. H. Reek and T. Noël, Oxidant-Free Amidation of Aldehydes Enabled by Electrophotocatalysis, Chem. – Eur. J., 2025 DOI:10.1002/chem.202502237.
9. Selected reports on photoelectrocatalytic C–O cross-coupling: (a) H. Huang and T. H. Lambert, Electrophotocatalytic C-H Heterofunctionalization of Arenes, Angew. Chem., Int. Ed., 2021, 60, 11163–11167; (b) T. Shen, Y.-L. Li, K.-Y. Ye and T. H. Lambert, Electrophotocatalytic oxygenation of multiple adjacent C–H bonds, Nature, 2023, 614, 275–280; (c) J. Zhang, Z. Yang, C. Liu, H. Wan, Z. Hao, X. Ji, P. Wang, H. Yi and A. Lei, Tailoring photocatalysts to modulate oxidative potential of anilides enhances para-selective electrochemical hydroxylation, Nat. Commun., 2024, 15, 6954; (d) J. Yin, C. Shi, A.-M. Hu, M. Luo, C. Yang, L. Guo and W. Xia, Copper-catalyzed C(sp³)−H amination and etherification of unactivated hydrocarbons via photoelectrochemical pathway, Nat. Commun., 2025, 16, 5123.
10. Selected reports on photoelectrocatalytic C–P cross-coupling: (a) J.-H. Wang, X.-B. Li, J. Li, T. Lei, H.-L. Wu, X.-L. Nan, C.-H. Tung and L.-Z. Wu, Photoelectrochemical cell for P–H/C–H cross-coupling with hydrogen evolution, Chem. Commun., 2019, 55, 10376–10379; (b) N. G. W. Cowper, C. P. Chernowsky, O. P. Williams and Z. K. Wickens, Potent Reductants via Electron-Primed Photoredox Catalysis: Unlocking Aryl Chlorides for Radical Coupling, J. Am. Chem. Soc., 2020, 142, 2093–2099; (c) J. Wang, C. Yang, H. Gao, L. Zuo, Z. Guo, P. Yang, S. Li and Z. Tang, Customized Photoelectrochemical C-N and C-P Bond Formation Enabled by Tailored Deposition on Photoanodes, Angew. Chem., Int. Ed., 2024, 63, e202408901; (d) K.-N. Yuan, T. Xie, J.-B. Wang, D. Wang and M. Shang, Photoelectrocatalyzed Alkylation of Phosphonites by Direct Decarboxylative C(sp³)-P Coupling, Angew. Chem., Int. Ed., 2025, 64, e202500744.
11. Selected reports on other photoelectrocatalytic C–heteroatom cross-coupling: (a) X.-R. Zhao, Y.-C. Zhang, Z.-W. Hou and L. Wang, Chloride-Promoted Photoelectrochemical C—H Silylation of Heteroarenes, Chin. J. Chem., 2023, 41, 2963–2968; (b) L. Zhao, J. Yang, K. Yan, X. Cheng, Z. Sun and J. Wen, Photoelectrochemical-induced heterogeneous catalytic selective dehalogenation coupling of alkyl halides with thiophenols via interfacial charge transfer, Green Chem., 2025, 27, 5581–5590.
12. Selected reports on photoelectrocatalytic functionalization of unsaturated moieties: (a) H. Huang and T. H. Lambert, Electrophotocatalytic Acetoxyhydroxylation of Aryl Olefins, J. Am. Chem. Soc., 2021, 143, 7247–7252; (b) L. Zeng, J.-H. Qin, G.-F. Lv, M. Hu, Q. Sun, X.-H. Ouyang, D.-L. He and J.-H. Li, Electrophotocatalytic Reductive 1,2-Diarylation of Alkenes with Aryl Halides and Cyanoaromatics, Chin. J. Chem., 2023, 41, 1921–1930; (c) X.-L. Lai and H.-C. Xu, Photoelectrochemical Asymmetric Catalysis Enables Enantioselective Heteroarylcyanation of Alkenes via C–H Functionalization, J. Am. Chem. Soc., 2023, 145, 18753–18759; (d) P. Xiong, S. I. Ivlev and E. Meggers, Photoelectrochemical asymmetric dehydrogenative [2 + 2] cycloaddition between C–C single and double bonds via the activation of two C(sp³)–H bonds, Nat. Catal., 2023, 6, 1186–1193; (e) J. M. Edgecomb, S. N. Alektiar, N. G. W. Cowper, J. A. Sowin and Z. K. Wickens, Ketyl Radical Coupling Enabled by Polycyclic Aromatic Hydrocarbon Electrophotocatalysts, J. Am. Chem. Soc., 2023, 145, 20169–20175; (f) S. Schmid, S. Wu, I. Dey, M. Domański, X. Tian and J. P. Barham, Photoelectrochemical Heterodifunctionalization of Olefins: Carboamidation Using Unactivated Hydrocarbons, ACS Catal., 2024, 14, 9648–9654; (g) L. Wang, X. Huo, X. He, L. Ackermann and D. Wang, Photoelectrochemical nickel-catalyzed carboacylation/silanoylation of alkenes with unactivated C/Si–H bonds, Green Chem., 2024, 26, 8315–8322; (h) Z.-M. Zong, M. Wang, X.-J. Zhao and Y. He, Bromide-catalyzed oxo-amination of alkenes towards the synthesis of α-amine ketones under photoelectrocatalysis conditions, Org. Chem. Front., 2024, 11, 3525–3530; (i) L. Zou, X. Zheng, X. Yi and Q. Lu, Asymmetric paired oxidative and reductive catalysis enables enantioselective alkylarylation of olefins with C(sp³)−H bonds, Nat. Commun., 2024, 15, 7826.
13. Selected reports on other elegant photoelectrocatalytic transformations: (a) W. Zhang, K. L. Carpenter and S. Lin, Electrochemistry Broadens the Scope of Flavin Photocatalysis: Photoelectrocatalytic Oxidation of Unactivated Alcohols, Angew. Chem., Int. Ed., 2020, 59, 409–417; (b) X. Tian, T. A. Karl, S. Reiter, S. Yakubov, R. de Vivie-Riedle, B. König and J. P. Barham, Electro-mediated PhotoRedox Catalysis for Selective C(sp³)–O Cleavages of Phosphinated Alcohols to Carbanions, Angew. Chem., Int. Ed., 2021, 60, 20817–20825; (c) C. P. Chernowsky, A. F. Chmiel and Z. K. Wickens, Electrochemical Activation of Diverse Conventional Photoredox Catalysts Induces Potent Photoreductant Activity, Angew. Chem., Int. Ed., 2021, 60, 21418–21425; (d) Z. Yang, D. Yang, J. Zhang, C. Tan, J. Li, S. Wang, H. Zhang, Z. Huang and A. Lei, Electrophotochemical Ce-Catalyzed Ring-Opening Functionalization of Cycloalkanols under Redox-Neutral Conditions: Scope and Mechanism, J. Am. Chem. Soc., 2022, 144, 13895–13902; (e) W.-J. Kang, Y. Zhang, B. Li and H. Guo, Electrophotocatalytic hydrogenation of imines and reductive functionalization of aryl halides, Nat. Commun., 2024, 15, 655; (f) P. Zhou, L. Ding, Y. Liu, H. Song and Q. Wang, Iron-Catalyzed Electrophotochemical α-Functionalization of a Silylcyclobutanol, Org. Lett., 2024, 26, 7094–7099; (g) Z.-R. Liu, X.-Y. Zhu, J.-F. Guo, C. Ma, Z. Zuo and T.-S. Mei, Synergistic use of photocatalysis and convergent paired electrolysis for nickel-catalyzed arylation of cyclic alcohols, Sci. Bull., 2024, 69, 1866–1874; (h) A. Shi, P. Xie, Y. Wang and Y. Qiu, Photoelectrocatalytic Cl-mediated C(sp³)–H aminomethylation of hydrocarbons by BiVO₄ photoanodes, Nat. Commun., 2025, 16, 2322; (i) G.-C. Yuan, M.-G. Li, S. Yang, K. Song, C.-X. Gong, S.-J. Zhu, Y. Li and K.-Y. Ye, Electrophotocatalytic decarbonylative [4 + 2] cyclization of indenones, Chin. Chem. Lett., 2025 DOI:10.1016/j.cclet.2025.111709.
14. Selected reviews: (a) M. D. Delost, D. T. Smith, B. J. Anderson and J. T. Njardarson, From Oxiranes to Oligomers: Architectures of U.S. FDA Approved Pharmaceuticals Containing Oxygen Heterocycles, J. Med. Chem., 2018, 61, 10996–11020; (b) S. Pathania, R. K. Narang and R. K. Rawal, Role of sulphur-heterocycles in medicinal chemistry: An update, Eur. J. Med. Chem., 2019, 180, 486–508; (c) C. M. Marshall, J. G. Federice, C. N. Bell, P. B. Cox and J. T. Njardarson, An Update on the Nitrogen Heterocycle Compositions and Properties of U.S. FDA-Approved Pharmaceuticals (2013–2023), J. Med. Chem., 2024, 67, 11622–11655.
15. Selected reviews on photo- or electrochemical heterocycle synthesis: (a) R. Francke, Recent advances in the electrochemical construction of heterocycles, Beilstein J. Org. Chem., 2014, 10, 2858–2873; (b) J.-R. Chen, X.-Q. Hu, L.-Q. Lu and W.-J. Xiao, Exploration of Visible-Light Photocatalysis in Heterocycle Synthesis and Functionalization: Reaction Design and Beyond, Acc. Chem. Res., 2016, 49, 1911–1923; (c) Y. Jiang, K. Xu and C. Zeng, Use of Electrochemistry in the Synthesis of Heterocyclic Structures, Chem. Rev., 2018, 118, 4485–4540; (d) V. Srivastava, P. K. Singh, S. Tivari and P. P. Singh, Visible light photocatalysis in the synthesis of pharmaceutically relevant heterocyclic scaffolds, Org. Chem. Front., 2022, 9, 1485–1507; (e) K. Titenkova, D. A. Chaplygin and L. L. Fershtat, Electrochemical Generation of Nitrogen-centered Radicals and its Application for the Green Synthesis of Heterocycles, ChemElectroChem, 2024, 11, e202400395; (f) B. Huang, Photo- and electro-chemical synthesis of substituted pyrroles, Green Chem., 2024, 26, 11773–11796; (g) B. Huang, Photo- and electro-chemical strategies for indazole synthesis, Tetrahedron Chem, 2024, 12, 100116; (h) S. Ghara, P. Barik, S. Ghosh, S. Ghosh, A. Mandal, C. Pramanik, M. Ikbal, S. Dhara and S. Samanta, UV/visible light-promoted external photocatalyst-free transformations: A Decade's Journey of N-heterocycles and their functionalisation, Org. Chem. Front., 2025, 12, 2790–2837.
16. Selected reviews on photoinduced LMCT catalysis: (a) Y. Abderrazak, A. Bhattacharyya and O. Reiser, Visible-Light-Induced Homolysis of Earth-Abundant Metal-Substrate Complexes: A Complementary Activation Strategy in Photoredox Catalysis, Angew. Chem., Int. Ed., 2021, 60, 21100–21115; (b) F. Juliá, Ligand-to-Metal Charge Transfer (LMCT) Photochemistry at 3d-Metal Complexes: An Emerging Tool for Sustainable Organic Synthesis, ChemCatChem, 2022, 14, e202200916; (c) H. Zhang, D. Wei, K. Xu and C. Zeng, Electrophotochemical ligand-to-metal charge transfer catalysis: an emerging platform for sustainable synthesis, Green Chem., 2025, 27, 3413–3430.
17. Selected reviews on interfacial photoelectrochemistry and its applications in organic synthesis: (a) J. P. Barham and B. König, Synthetic Photoelectrochemistry, Angew. Chem., Int. Ed., 2020, 59, 2–18; (b) T. Hardwick, A. Qurashi, B. Shirinfar and N. Ahmed, Interfacial Photoelectrochemical Catalysis: Solar-Induced Green Synthesis of Organic Molecules, ChemSusChem, 2020, 13, 1967–1973; (c) Y.-C. Wu, R.-J. Song and J.-H. Li, Recent advances in photoelectrochemical cells (PECs) for organic synthesis, Org. Chem. Front., 2020, 7, 1895–1902; (d) G. Chan, D. Corsi, O. Savateev, P. Giusto and J. P. Barham, Interfacial Photoelectrochemistry in Organic Synthesis, Angew. Chem., Int. Ed., 2025 DOI:10.1002/anie.202424300.
18. Selected reports on photoelectrochemical alkene epoxidation: (a) X. Liu, Z. Chen, S. Xu, G. Liu, Y. Zhu, X. Yu, L. Sun and F. Li, Bromide-Mediated Photoelectrochemical Epoxidation of Alkenes Using Water as an Oxygen Source with Conversion Efficiency and Selectivity up to 100%, J. Am. Chem. Soc., 2022, 144, 19770–19777; (b) Y. Zhao, M. Duan, C. Deng, J. Yang, S. Yang, Y. Zhang, H. Sheng, Y. Li, C. Chen and J. Zhao, Br⁻/BrO⁻-mediated highly efficient photoelectrochemical epoxidation of alkenes on α-Fe₂O₃, Nat. Commun., 2023, 14, 1943; (c) D. Tang, K. Dang, J. Wang, C. Chen, J. Zhao and Y. Zhang, Solar-driven green synthesis of epoxides, Sci. China: Chem., 2023, 66, 3415–3425; (d) Q. Wang, L. Wu, H. Shi and J. Luo, Surface Engineered BiVO₄ for Photoelectrochemical Alkene Epoxidation via Bromine Mediation, ACS Energy Lett., 2025, 10, 2026–2034; (e) H. Wu, Y. Wang, M. Huang, J. Cheng, B. Sa, Y. Fang and X. Wang, Alkene Epoxidation with Water by Confined Active Co Sites on BiVO₄ Photoanodes under Visible Light, Angew. Chem., Int. Ed., 2025, 64, e202420188; (f) Z. Chen, Y. Zhu, X. Li, Z. Wen, H. Gao, R. Zhao, S. Wang, S. He, Y. Guo, L. Sun and F. Li, Photoelectrochemical Asymmetric Epoxidation of Alkenes with Water as an Oxygen Source in a Biphasic System, J. Am. Chem. Soc., 2025, 147(33), 30154–30162.
19. H. Huang, Z. M. Strater, M. Rauch, J. Shee, T. J. Sisto, C. Nuckolls and T. H. Lambert, Electrophotocatalysis with a Trisaminocyclopropenium Radical Dication, Angew. Chem., Int. Ed., 2019, 58, 13318–13322.
20. T. Shen and T. H. Lambert, Electrophotocatalytic diamination of vicinal C-H bonds, Science, 2021, 371, 620–626.
21. H. Huang and T. H. Lambert, Regiodivergent Electrophotocatalytic Aminooxygenation of Aryl Olefins, J. Am. Chem. Soc., 2022, 144, 18803–18809.
22. Selected reviews on HAT chemistry: (a) L. Capaldo and D. Ravelli, Hydrogen Atom Transfer (HAT): A Versatile Strategy for Substrate Activation in Photocatalyzed Organic Synthesis, Eur. J. Org. Chem., 2017, 2056–2071; (b) H. Cao, X. Tang, H. Tang, Y. Yuan and J. Wu, Photoinduced intermolecular hydrogen atom transfer reactions in organic synthesis, Chem Catal., 2021, 1, 523–598; (c) L. Chang, S. Wang, Q. An, L. Liu, H. Wang, Y. Li, K. Feng and Z. Zuo, Resurgence and advancement of photochemical hydrogen atom transfer processes in selective alkane functionalizations, Chem. Sci., 2023, 14, 6841–6859; (d) J.-L. Tu and B. Huang, Direct C(sp³)–H functionalization with aryl and alkyl radicals as intermolecular hydrogen atom transfer (HAT) agents, Chem. Commun., 2024, 60, 11450–11465; (e) J.-L. Tu and B. Huang, Acyloxy, sulfate, and phosphate radicals as hydrogen atom transfer (HAT) agents for direct C(sp³)–H functionalization, RSC Sustainability, 2024, 2, 3222–3234; (f) H.-S. Wang, L. Li, X. Chen, J.-L. Wu, K. Sun, X.-L. Chen, L.-B. Qu and B. Yu, Recent advances in amidyl radical-mediated photocatalytic direct intermolecular hydrogen atom transfer, Beilstein J. Org. Chem., 2025, 21, 1306–1323.
23. L.-Q. Ren, N. Li, J. Ke and C. He, Recent advances in photo- and electro-enabled radical silylation, Org. Chem. Front., 2022, 9, 6400–6415.
24. Q. Wan, C.-Y. Huang, Z.-W. Hou, H. Jiang and L. Wang, Organophotoelectrochemical silylation cyclization for the synthesis of silylated 3-CF₃-2-oxindoles, Org. Chem. Front., 2023, 10, 3585–3590.
25. H. He, Q. Wan, Z.-W. Hou, Q. Zhou and L. Wang, Organoelectrophotocatalytic Generation of Acyl Radicals from Formamides and Aldehydes: Access to Acylated 3-CF₃-2-Oxindoles, Org. Lett., 2023, 25, 7014–7019.
26. (a) T. Koike and M. Akita, New Horizons of Photocatalytic Fluoromethylative Difunctionalization of Alkenes, Chem, 2018, 4, 409–437; (b) R. Shaw, N. Sihag, H. Bhartiya and M. R. Yadav, Harnessing photocatalytic and electrochemical approaches for C–H bond trifluoromethylation and fluoroalkylation, Org. Chem. Front., 2024, 11, 954–1014; (c) S. Kim and H. Kim, Electrochemical Access to Difluoromethyl Groups: An Overview of Scope, Mechanisms, and Challenges, ACS Catal., 2025, 15, 6826–6851.
27. D. Chen, X. Yang, D. Wang, Y. Li, L. Shi and D. Liang, Electrophotocatalytic tri- or difluoromethylative cyclization of alkenes, Org. Chem. Front., 2023, 10, 2482–2490.
28. (a) M. Zhang, Z. Luo, X. Tang, L. Yu, J. Pei, J. Wang, C. Lu and B. Huang, Electrochemical selenocyclization of 2-ethynylanilines with diselenides: facile and efficient access to 3-selenylindoles, Org. Biomol. Chem., 2023, 21, 8918–8923; (b) J. Liu, J.-P. Wan and Y. Liu, Electrochemical difunctionalization of alkenes and alkynes for the synthesis of organochalcogens involving C–S/Se bond formation, Org. Chem. Front., 2024, 11, 597–630; (c) X. Ma, Y. Zhang, X. Fang, X. Yang, P. Zhou, S. Lu and C. Shu, Four-component radical-polar crossover cyclization involving double insertion of SO₂ to β-sulfonyl sultines, Org. Chem. Front., 2024, 11, 7153–7161; (d) J. Wang, G. Gao, C. Shi, H. Gao, J. Luo, G. Wei, D. Zhang, H. Li, T. Yang and B. Huang, Visible-light induced direct C(sp³)–H bond disulfidation of saturated N-heterocycles through a hydrogen atom transfer (HAT) process, Org. Chem. Front., 2025, 12, 2286–2291; (e) J. Cai, Z. Zeng, Q.-L. Wang and W. Li, Recent Advances in the Assembly of Organoselenyl-Substituted (Thio)Chromones and 4-Quinolones, Adv. Synth. Catal., 2025, 367, e202500210.
29. K. Gong, Y. Ma, P. Yu, S. Gao, Y. Li, D. Liang, S. Sun and B. Wang, Self- or Acridinium-Catalyzed Electrophotosynthesis of Thiocyanato Heterocycles from Activated Alkenes, Adv. Synth. Catal., 2024, 366, 2352–2362.
30. D. Wang, L. Zeng, J. Shi, S. Gao, L. Shi, S. Sun and D. Liang, Electrophotocatalysis Versus Indirect Electrolysis: Electrochemical Selenocyclization of 3-Aza-1,5-dienes Facilitated by Energy Transfer, Direct Photolysis or N-Hydroxyphthalimide, Chem. – Eur. J., 2024, 30, e202400280.
31. L. Ding, G. Yang, L. Luo, Y. Ma, J. Shi, D. Liang and Y. Li, DABCO-Mediated Photoelectrochemical Three-Component Sulfonocyclization of 3-Aza-1,5-dienes, Chin. J. Chem., 2025, 43, 491–500.
32. W. Xiao, J.-Q. Chen and J. Wu, Radical sulfonylation with sulfur dioxide surrogates, Chem. Soc. Rev., 2025, 54, 6832–6926.
33. Y. Ma, P. Yu, R. Qin, R. He, L. Zeng, L. Shi, S. Sun and D. Liang, Electrophotocatalytic Thiocyanation and Sulfonylation Cyclization of Unactivated Alkenes, J. Org. Chem., 2025, 90, 598–613.
34. Selected reviews on photo-/electrochemical direct C(sp³)–H functionalization: (a) Z. Yang, W. Shi, H. Alhumade, H. Yi and A. Lei, Electrochemical oxidative C(sp³)–H cross-coupling with hydrogen evolution, Nat. Synth., 2023, 2, 217–230; (b) J. Zhang and M. Rueping, Metallaphotoredox catalysis for sp³ C–H functionalizations through single-electron transfer, Nat. Catal., 2024, 7, 963–976; (c) P. Singh, B. König and A. C. Shaikh, Electro-photochemical Functionalization of C(sp³)–H bonds: Synthesis toward Sustainability, JACS Au, 2024, 4, 3340–3357; (d) J.-L. Tu, Y. Zhu, P. Li and B. Huang, Visible-light induced direct C(sp³)–H functionalization: recent advances and future prospects, Org. Chem. Front., 2024, 11, 5278–5305.
35. M. Tao, Q. Feng, K. Gong, X. Yang, L. Shi, Q. Chang and D. Liang, Photoredox streamlines electrocatalysis: photoelectrosynthesis of polycyclic pyrimidin-4-ones through carbocyclization of unactivated alkenes with malonates, Green Chem., 2024, 26, 4199–4208.
36. P. R. D. Murray, J. H. Cox, N. D. Chiappini, C. B. Roos, E. A. McLoughlin, B. G. Hejna, S. T. Nguyen, H. H. Ripberger, J. M. Ganley, E. Tsui, N. Y. Shin, B. Koronkiewicz, G. Qiu and R. R. Knowles, Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis, Chem. Rev., 2022, 122, 2017–2291.
37. (a) M. Balci, Recent advances in the synthesis of fused heterocycles with new skeletons via alkyne cyclization, Tetrahedron Lett., 2020, 61, 151994; (b) M. Chen, J. Wang, Y. Kan, X. Jia, B. Huang, T. Li and X. Zhao, Electrocatalytic [3 + 2] Annulation for the Synthesis of Polysubstituted Furans, Org. Lett., 2023, 25, 4540–4545; (c) B. Huang, G. Chen, H. Zhang, X. Tang, J. Yuan, C. Lu and J. Wang, Divergent electrosynthesis of 3-iodoindoles and indoles from 2-ethynylanilines under ambient and aqueous conditions, Org. Chem. Front., 2023, 10, 3515–3521; (d) P. Kushwaha, A. Saxena, T. von Münchow, S. Dana, B. Saha and L. Ackermann, Metallaelectro-catalyzed alkyne annulations via C–H activations for sustainable heterocycle syntheses, Chem. Commun., 2024, 60, 12333–12364; (e) K. Nagesh, N. S. Reddy, S. Kareem, S. R. Vali and B. V. S. Reddy, Recent advances in transition metal-catalyzed alkyne annulations: applications in organic synthesis, Org. Biomol. Chem., 2025, 23, 6665–6682; (f) J. Peng, Q. Chen, X. Wu, R. Zhan, Y. Chen, M. Ji, C. Lu, J. Wang, F. Jiang and B. Huang, Electrochemical seleno-/tellurocyclization of propargyl carboxylic acids, Chem. Commun., 2025, 61, 12357–12360.
38. Y.-Y. Cheng, J. Xu, Z. Lin, Y. Li and L. Ackermann, Photoelectrocatalytic [4 + 2] Annulation for S-Heterocycle Assembly Enabled by Proton-Coupled Electron Transfer (PCET), Chem. – Eur. J., 2024, 30, e202402333.
39. (a) G. E. M. Crisenza, D. Mazzarella and P. Melchiorre, Synthetic Methods Driven by the Photoactivity of Electron Donor–Acceptor Complexes, J. Am. Chem. Soc., 2020, 142, 5461–5476; (b) T. Tasnim, M. J. Ayodele and S. P. Pitre, Recent Advances in Employing Catalytic Donors and Acceptors in Electron Donor–Acceptor Complex Photochemistry, J. Org. Chem., 2022, 87, 10555–10563; (c) J. Wang, G. Gao, J. Cheng, J. Li, X. Chen, X. Chen, D. Zhang, H. Li, X. Cai and B. Huang, Photocatalytic organosulfur reagent-promoted selective mono-(deutero)hydrodechlorination, Green Chem., 2024, 26, 5167–5172; (d) S. Choudhury and S. R. Roy, Photoinduced Single Electron Transfer via EDA Complexation Enables Decarbonylative C(sp²)–S Bond Formation, Org. Lett., 2024, 26, 10158–10164; (e) H. F. Piedra, I. Tagarro and M. Plaza, EDA complex photochemistry as a strategy for C–S bond formation, Org. Chem. Front., 2025, 12, 3920–3941.
40. P. P. Sen, N. Saha and S. R. Roy, Investigating the Potency of a Phenalenyl-Based Photocatalyst under the Photoelectrochemical Condition for Intramolecular C–S Bond Formation, ACS Catal., 2024, 14, 907–920.
41. (a) Q. An, Y.-Y. Xing, R. Pu, M. Jia, Y. Chen, A. Hu, S.-Q. Zhang, N. Yu, J. Du, Y. Zhang, J. Chen, W. Liu, X. Hong and Z. Zuo, Identification of Alkoxy Radicals as Hydrogen Atom Transfer Agents in Ce-Catalyzed C–H Functionalization, J. Am. Chem. Soc., 2023, 145, 359–376; (b) J.-L. Tu, A.-M. Hu, L. Guo and W. Xia, Iron-Catalyzed C(Sp³)–H Borylation, Thiolation, and Sulfinylation Enabled by Photoinduced Ligand-to-Metal Charge Transfer, J. Am. Chem. Soc., 2023, 145, 7600–7611; (c) X.-Y. Yuan, C.-C. Wang and B. Yu, Recent advances in FeCl₃-photocatalyzed organic reactions via hydrogen-atom transfer, Chin. Chem. Lett., 2024, 35, 109517; (d) B. Huang, X. Tang, J. Yuan, M. Zhang, Z. Luo, J. Wang and C. Lu, Visible-light induced selenocyclization of 2-ethynylanilines under ambient conditions: simple FeBr₃ as a dual-functional catalyst, Org. Biomol. Chem., 2024, 22, 6198–6204; (e) J. Qin, H. Lei, C. Gao, Y. Zheng, Y. Zhao and W. Xia, Light-induced ligand-to-metal charge transfer of Fe(III)-OR species in organic synthesis, Org. Biomol. Chem., 2024, 22, 6034–6044; (f) J.-L. Tu and B. Huang, Titanium in photocatalytic organic transformations: current applications and future developments, Org. Biomol. Chem., 2024, 22, 6650–6664; (g) P. C. Tiwari, A. Pulcinella, E. Hodžić and T. Noël, Late-Stage Heteroarene Alkylation via Minisci Reaction with Gaseous Alkanes Enabled by Hydrogen Atom Transfer in Flow, ACS Cent. Sci., 2025, 11, 910–917.
42. Y. Jiang, K. Xu and C. Zeng, Electrophotocatalytic Si–H Activation Governed by Polarity-Matching Effects, CCS Chem., 2022, 4, 1796–1805.
43. Z. Tan, Y. Jiang, K. Xu and C. Zeng, Electrophotoredox/cerium-catalyzed unactivated alkanes activation for the sustainable synthesis of alkylated benzimidazo-fused isoquinolinones, J. Catal., 2023, 417, 473–480.
44. M. Wang, D. Wang, K. Xu and C. Zeng, Electrophotoredox cerium-catalyzed decarboxylative radical cyclization cascade for the synthesis of alkylated benzimidazo-fused isoquinolinones, Catal. Sci. Technol., 2024, 14, 1037–1042.
45. Selected reviews on photo- or electrochemical decarboxylative functionalization of carboxylic acids: (a) V. Ramadoss, Y. Zheng, X. Shao, L. Tian and Y. Wang, Advances in Electrochemical Decarboxylative Transformation Reactions, Chem. – Eur. J., 2021, 27, 3213–3228; (b) L. Li, Y. Yao and N. Fu, Free Carboxylic Acids: The Trend of Radical Decarboxylative Functionalization, Eur. J. Org. Chem., 2023, e202300166; (c) J.-L. Tu, Z. Shen and B. Huang, Light-Induced Direct Decarboxylative Functionalization of Aromatic Carboxylic Acids, Adv. Synth. Catal., 2024, 366, 4263–4273; (d) C.-L. Ji, Y.-N. Lu, S. Xia, C. Zhu, C. Zhu, W. Li and J. Xie, Photoinduced Late-Stage Radical Decarboxylative and Deoxygenative Coupling of Complex Carboxylic Acids and Their Derivatives, Angew. Chem., Int. Ed., 2025, 64, e202423113.
46. J.-L. Tu and B. Huang, Catalytic Construction of C(sp³)-Ge Bonds: Recent Advances and Future Perspectives, Adv. Synth. Catal., 2024, 366, 4618–4633.
47. W. Wei, S. L. Homölle, T. von Münchow, Y. Li, I. Maksso and L. Ackermann, Photoelectrochemical Si–H and Ge–H activation by iron catalysis, Cell Rep. Phys. Sci., 2023, 4, 101550.
48. (a) S. Sarkar, K. P. S. Cheung and V. Gevorgyan, C–H functionalization reactions enabled by hydrogen atom transfer to carbon-centered radicals, Chem. Sci., 2020, 11, 12974–12993; (b) W. Guo, Q. Wang and J. Zhu, Visible light photoredox-catalysed remote C–H functionalisation enabled by 1,5-hydrogen atom transfer (1,5-HAT), Chem. Soc. Rev., 2021, 50, 7359–7377; (c) J. Wang, Q. Xie, G. Gao, H. Li, W. Lu, X. Cai, X. Chen and B. Huang, Selective N-α-C–H alkylation of cyclic tertiary amides via visible-light-mediated 1,5-hydrogen atom transfer, Org. Chem. Front., 2023, 10, 4394–4399; (d) J. Wang, Q. Xie, G. Gao, G. Wei, X. Wei, X. Chen, D. Zhang, H. Li and B. Huang, Visible-light-mediated synthesis of polysubstituted pyrroles via C_Ar–I reduction triggered 1,5-hydrogen atom transfer process, Org. Chem. Front., 2024, 11, 4522–4528; (e) Y.-L. Chu, L. Zeng, S. Wu, J. Yang, M. Hu and J.-H. Li, A photocatalytic hydrogen atom transfer and aryl migration strategy for the arylalkylation of activated alkenes with 1-(o-iodoaryl)-alkan-1-ones, Org. Chem. Front., 2025, 12, 4424–4429; (f) Z. Li, W. Yan, X. Zhou, C. Yang, L. Guo and W. Xia, Multicomponent synthesis of unsymmetrical 1,2-diamines via photo-induced carbonyl alkylative amination, Org. Chem. Front., 2025 10.1039/d5qo00479a.
49. F. Wang and S. S. Stahl, Merging Photochemistry with Electrochemistry: Functional-Group Tolerant Electrochemical Amination of C(sp³)-H Bonds, Angew. Chem., Int. Ed., 2019, 58, 6385–6390.
50. M. Gong, M. Huang, Y. Li, J. Zhang, J. K. Kim, J. S. Kim and Y. Wu, Harnessing visible-light energy for unbiased organic photoelectrocatalysis: synthesis of N-bearing fused rings, Green Chem., 2022, 24, 837–845.
51. H. Li, K. Qiao, W. Jiang, F. Li and L. Shi, Dehydrogenative cyclization of 2-arylbenzoic acid and 2-arylbenzamide with hydrogen evolution in a photoelectrochemical cell, Chem. Commun., 2024, 60, 9416–9419.
52. A. Choi, D. Kim, D. Yim, J. Park, A. Sharma, W. Kim, H. Kim and H. Kim, Photon-Primed Organic Electrosynthesis Enabled by Oxidation of Photon-Induced Intermediates, J. Am. Chem. Soc., 2025, 147, 30897–30906.

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