EDA Complexes Research Articles

Visible‐Light‐Induced Deaminative Alkylation for the Synthesis of Chroman‐4‐One Derivatives via EDA Complexes

AbstractA visible‐light‐mediated synthesis of 3‐alkyl‐ substituted chroman‐4‐one derivatives via deaminative alkylation of amino acid derived Katritzky salts and tandem cyclization with o‐(allyloxy)arylaldehydes has been developed. This approach exhibits functional‐group compatibility with 31 examples and affords the desired products in yields of 16–88%. Mechanistic research results suggest that the formation of EDA complexes between the Katritzky salts and a base is the main reason for initiating the reaction.

Visible-Light Driven Synthesis of Vinyl Amines without Photocatalyst.

We developed a visible-light-induced vinyl amination of activated alkenes using TMSN3 and CsF through EDA complex formation under an oxygen atmosphere. Without light, the EDA complex forms between activated alkene, CsF, and oxygen. Upon exposure to light, oxygen in the complex gets excited, initiating the HAT process. This method efficiently synthesizes vinyl-amine derivatives via a radical pathway, demonstrating good functional group tolerance and high yields in a short time. Further, the late-stage functionalization enables the synthesis of biologically active heterocycles.

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Simple reaction, useful chemistry. The electron donor‐acceptor complex (EDA) photochemistry provides a simple and efficient platform for organic synthesis. A general EDA complex strategy formed by readily accessible thiophenolate anion and oxime ester successfully realizes the diverse synthesis of thioethers under visible light irradiation. Such a strategy could also enable a thiol‐catalysis for the synthesis of phenanthridines. More details are discussed in the article by Zhong et al. on pages 2751—2756. image

On the role of thermally activated EDA complexes in decarboxylative cross-coupling

Decarboxylative cross-coupling using NHPI esters involves reductive fragmentation initiated by electron transfer. A recent report described iron(II) porphyrins as competent reductants despite their low oxidation potentials. Here we briefly describe how this may occur.

Formate‐Mediated Synthesis of β‐Hydroxysulfides from Olefins and Thiosulfonates via EDA Complex Strategy under Visible Light Irradiation in Air

Comprehensive SummaryA visible‐light‐induced and efficient one‐pot synthesis of β‐hydroxysulfides from olefins, thiosulfonates and HCOOCs using an EDA complex strategy under air atmosphere at room temperature has been disclosed. A plausible radical involved mechanism is proposed. During the reaction process, formates play a crucial role: first, as donors in the EDA complex; second, as providers of the hydrogen source; and third, by generating CO2•– to reduce peroxide intermediates, leading to the formation of β‐hydroxysulfides. In contrast to the previously reported thiol‐oxygen co‐oxidation reactions, this simple and sustainable approach features mild reaction conditions, operational simplicity, odorless and excellent functional group tolerance.

EDA Complex-Enabled Annulation to Access CF2-Containing Tetralones and Quinazolinones Using Persulfates as Electron Donors.

A photocatalyst-free and EDA complex-enabled radical cascade cyclization reaction of inactive alkenes with bromodifluoroacetamides was reported for the divergent synthesis of fluorine-containing tetralones and quinazolinones. In this transformation, persulfates as electron donors and difluoro bromamide as electron acceptors generate the EDA complex. This is a promising photochemical method with advantages such as mild reaction conditions, simple operation, being metal-free, and excellent functional group tolerance.

Visible‐Light Induced C‐3 Carbamoylation of Quinoxalinones Assisted by EDA Complex

AbstractA visible‐light‐promoted strategy for the decarboxylative C‐3 carbamoylation of quinoxalinone scaffolds is developed. This approach initiates through the formation of an EDA complex between oxamic acid and quinoxalinone. Successive SET and decarboxylative carbamoylation construct the C−C bond. This method utilizes aerial oxygen as the green oxidant and eradicates the process from the use of external photocatalysts and transition metals. Detailed synthetic and photophysical studies enlighten the reaction pathway.

A General Electron Donor‐Acceptor Photoactivation Using Oxime Esters Enabled Divergent Thioetherifications†

Comprehensive SummaryThe EDA complex‐mediated reactions involving oxime esters have been few studied. Herein, an EDA complex formed by thiophenolate anion and oxime ester is reported for photoinduced divergent synthesis of thioethers, depending on different types of oxime esters. Operational simplicity, mild reaction conditions, and flexible options of leaving group demonstrate the generality and synthetic utility of this approach. Such an approach can also enable an interesting thiol‐catalysis for the synthesis of phenanthridines.

Correction to “Photochemical Reductive Carboxylation of N-Benzoyl Imines with Oxalate Accelerated by Formation of EDA Complexes”

Correction to “Photochemical Reductive Carboxylation of <i>N</i>-Benzoyl Imines with Oxalate Accelerated by Formation of EDA Complexes”

Visible‐Light Mediated C‐3 Amination of Quinoxalin‐ 2(1H)‐ones via Electron Donor‐Acceptor Complexation

AbstractThe formation of carbon‐nitrogen bonds holds paramount importance in the realm of synthetic organic chemistry, finding extensive applications in the synthesis of pharmaceuticals, agrochemicals, and organic materials. Herein, we describe a novel EDA complex mediated, metal‐ and photocatalyst‐free, visible‐light‐initiated direct C‐3 amination of biologically important, quinoxalin‐2(1H)‐one moiety. The key to the success lies in the formation of a photoactivated electron donor‐acceptor complex between quinoxalin‐2(1H)‐one and amine, which undergo subsequent electron transfer reaction to effect the desired transformation. A diverse array of 3‐aminoquinoxalin‐2(1H)‐ones were prepared employing this process and the yields are up to 87%. This work represents a significant advancement toward a more environmentally friendly and efficient approach, characterized by mild reaction conditions and a high atom economy.

Expanding the Chemical Space of Electrophilic β-Glycosyl β-Lactams through Photoinduced Diastereoselective Functionalization.

Herein, we present a photoinduced diastereoselective C-3 functionalization of electrophilic β-glycosyl β-lactams. The developed protocol is simple, mild, and scalable and explores the use of 3-exomethylene β-lactams as reaction partners in a Giese type reaction. The key nucleophilic alkyl radical is generated by a photoinduced electron transfer process in the EDA complex formed by NHPI and Hantzsch esters. The diastereoselective hydrogen atom transfer to the β-lactam radical intermediate enables the synthesis of various N-phenyl β-glycosyl β-lactams.

EDA Complex-Promoted Cascade Cyclization of Alkynes Enabling the Rapid Assembly of 3-Sulfonylindoles and Vinyl Sulfone Oxindoles.

Herein, we disclose a photoinduced radical cascade cyclization of alkynes with sulfinates via a novel EDA complex for the synthesis of various 3-sulfonylindoles and vinyl sulfone oxindoles, which are crucial motifs in medicinal and biological chemistry. The reaction proceeds under mild, photocatalyst- and transition-metal-free conditions, featuring operational simplicity, broad substrate scope, and easy scalability. Mechanistic studies reveal that the reaction is initiated with a photoinduced intermolecular charge transfer from sulfinates to N-sulfonamides, generating a sulfonyl radical followed by an N-centered radical, thus enabling the cascade cyclization process.

Photochemical Reductive Carboxylation of N-Benzoyl Imines with Oxalate Accelerated by Formation of EDA Complexes

Photochemical Reductive Carboxylation of <i>N</i>-Benzoyl Imines with Oxalate Accelerated by Formation of EDA Complexes

Progress in Photocatalyzed Trifluoromethylthiolation and Trifluoromethylselenolation Reactions

AbstractThe trifluoromethylthio (SCF3) and trifluoromethylselanyl (SeCF3) groups possess high electron-withdrawing ability, excellent lipophilicity, good stability, and bioavailability, and they are promising structural motifs in drug design and development. Photoredox catalysis has clear benefits; it is a mild and sustainable methodology for the modification of chemical structures that enables a variety of chemical reactions that are unattainable using classical ionic chemistry. This review focuses on light-initiated trifluoromethylthiolation and trifluoromethylselenolation reactions with diverse SCF3 and SeCF3 reagents. Representative transformations either using photocatalysts or through EDA complexes, as well as possible reaction mechanisms, are all discussed in this article.1 Introduction2 Photocatalyzed Trifluoromethylthiolation2.1 Photocatalyzed Trifluoromethylthiolation with MSCF3 (M = H, [Me4N], Ag)2.2 Photocatalyzed Trifluoromethylthiolation with XSCF3 (X = Cl, CF3S)2.3 Photocatalyzed Trifluoromethylthiolation with ArSO2SCF3 2.4 Photocatalyzed Trifluoromethylthiolation with N–SCF3 Reagents2.5 Photocatalyzed Trifluoromethylthiolation with Other Reagents3 Photocatalyzed Trifluoromethylselenolation3.1 Photocatalyzed Trifluoromethylselenolation with [Me4N][SeCF3]3.2 Photocatalyzed Trifluoromethylselenolation with ArSO2SeCF3 4 Summary

Photocatalyst/metal-free sequential C–N/C–S bond formation: Synthesis of S-arylisothioureas via photoinduced EDA complex activation

A photocatalyst-free visible-light-promoted three-component reaction of thianthrenium salts, isothiocyanates, and amines is presented, which affords a rapid and efficient approach to S-arylisothioureas under mild conditions. This developed method exhibits the advantages of readily available raw materials, broad substrate scope, good functional tolerance, and operational simplicity. It is worth mentioning that the byproduct thianthrene can be recycled in quantity, ultimately maximizing the atomic economy of the reaction and avoiding chemical waste. Mechanism investigations support the strategy involving a photoinduced EDA complex.

Visible‐Light‐Induced Three‐Component Alkylpyridylation of Alkenes Enabled by Electron Donor‐Acceptor Complex

Visible‐light‐induced difunctionalization of alkenes is a powerful strategy for constructing complex molecules. Herein, we disclose a three‐component 1,2‐alkylpyridylation of alkenes under mild and photosensitizers‐free conditions. UV‐vis absorption spectroscopy studies and NMR titration experiments indicate that the formation of an EDA complex between 4‐alkyl‐DHPs and 4‐cyanopyridines. Primary, secondary, and tertiary C(sp3)‐centered radicals were formed by homolytic cleavage of 4‐alkyl‐DHPs. Gram‐scale synthesis and late‐stage functionalization of medicinally relevant molecules showed the synthetic potential of our methodology.

Cover Feature: Perfluoroalkylation of Triarylamines by EDA Complexes and Ulterior Sensitized [6π]‐Electrocyclization to Perfluoroalkylated Endo‐Carbazoles. Mechanistic and Photophysical Studies (Chem. Eur. J. 30/2024)

Cover Feature: Perfluoroalkylation of Triarylamines by EDA Complexes and Ulterior Sensitized [6π]‐Electrocyclization to Perfluoroalkylated <i>Endo</i>‐Carbazoles. Mechanistic and Photophysical Studies (Chem. Eur. J. 30/2024)

Photochemical Trifluoromethylative Difunctionalization of Styrenes and Phenylacetylenes via a Catalytic EDA Platform

AbstractHerein we report a visible‐light‐induced trifluoromethylative difunctionalization of styrenes and phenylacetylenes using trifluoromethyl thianthrenium triflate (TT‐CF3+OTf−). The transformation was enabled by the discovery of a photoactive catalytic EDA complex formed between carbazolyl dithiocarbamate and TT‐CF3+OTf−. This three‐component reactivity platform establishes a new paradigm for TT‐CF3+OTf−, significantly expanding its repertoire of photochemically enabled trifluoromethylation reactions.

Rational fabrication of Z-scheme heterojunction ZnFe2O4-seed@TpTt-COF for the visible-light-driven photocatalytic degradation of bisphenol A in food waste leachate boosted by primitive humic acid

Herein, we proposed a method by pre-embedding organic covalent organic framework TpTt-COF(TpTt) (consisting of the electron donor 1,3,5-triazine-2,4,6-triamine (Tt) and electron acceptor 2,4,6-triformylphloroglucinol (Tp) aldehyde) within inorganic ZnFe2O4 core to serve as seed for the in-situ grafting of organic TpTt shell tightly. The as-formed ZnFe2O4-seed@TpTt-COF (Z-S@TpTt) core–shell structure exhibited visible-light-driven photocatalytic degradation of BPA effectively. This may stem from the rationally tuned energy band structure of ZnFe2O4-seed via TpTt pre-anchoring, thus enabled a Z-scheme electron transfer way within the heterojunction to broaden the light adsorption, accelerate the charge transfer and maintain their thermodynamic redox capacity. More strikingly, humic acid (HA) in the actual wastewater (food waste leachate (FWL), where BPA highly frequently presented) could even boost the photocatalytic degradation of BPA. Comprehensive characterizations and DFT calculations revealed that HA acts as a critical “electron shuttle” to further promote the separation of electron-hole pairs via the formation of an EDA complex with the Z-S@TpTt. The gathered electrons on CB of ZnFe2O4-seed and holes on VB of TpTt may generate more •O2– and 1O2, thus the improved performance of Z-S@TpTt core–shell heterojunction in BPA degradation was achieved. Besides the promoted catalytical activity, the convenient separation ability and extraordinary chemical/thermal stability inherited from the magnetic core and the COF shell also enabled robust reuse of Z-S@TpTt heterojunction in FWL. All of these properties endowed Z-S@TpTt heterojunction with the practical application potential to remove BPA in an economical and environment-friendly way, which is also compatible with the “waste control by waste” strategy today.

Photocatalytic Radical Decarboxylation [4 + 3] Annulation Reactions of Lactones via Dienoic Acid EDA Complexes

Photocatalytic Radical Decarboxylation [4 + 3] Annulation Reactions of Lactones via Dienoic Acid EDA Complexes