Ligand‐to‐Metal Charge Transfer (LMCT) Photochemistry at 3d‐Metal Complexes: An Emerging Tool for Sustainable Organic Synthesis

ChemCatChem, Journal Year: 2022, Volume and Issue: 14(19)

Published: Aug. 11, 2022

Abstract Despite the rich photochemistry of 3d‐metal complexes, utilization excited‐state reactivity these compounds in organic synthesis has been historically overlooked. The advent photoredox catalysis changed perception synthetic chemists towards photochemistry, and nowadays potential photoinduced, outer‐sphere single‐electron transfer events is widely recognized. More recently, an emerging new mode photoactivation taken spotlight, based on inner‐sphere triggered by population ligand‐to‐metal charge‐transfer (LMCT) excited states. Contrarily to photoredox, LMCT‐activation does not rely matching redox potentials, offers unique profiles particularly well suited Earth‐abundant metal complexes. Those appealing features are propelling development methods using this blueprint generate highly reactive open‐shell species under mild conditions. aim contribution provide a didactical tool for comprehension concept facilitate methodologies achieve sustainable chemical transformations.

Language: Английский

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Acridinium Salts and Cyanoarenes as Powerful Photocatalysts: Opportunities in Organic Synthesis

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(36), P. 19526 - 19549

Published: April 22, 2021

The use of organic photocatalysts has revolutionized the field photoredox catalysis, as it allows access to reactivities that were traditionally restricted transition-metal photocatalysts. This Minireview reports recent developments in acridinium ions and cyanoarene derivatives synthesis. activation inert chemical bonds well late-stage functionalization biorelevant molecules are discussed, with a special focus on their mechanistic aspects.

Language: Английский

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Photoredox‐Catalyzed Defluorinative Functionalizations of Polyfluorinated Aliphatic Amides and Esters

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 61(9)

Published: Dec. 10, 2021

Abstract Selective C−F bond functionalization of perfluoalkyl units has huge potential towards accessing functionalized organofluorinated compounds, but remains challenging due to the high strength and inherent selectivity challenges. We report a new catalytic approach selective strong bonds in polyfluorinated aliphatic esters amides. This simple reaction proceeds mild operational fashion with divergent conversions, including hydrodefluorination, defluoroalkylation, defluoroalkenylation, affording diverse array important partially fluorinated motifs. Straightforward downstream chemistry alcohols, amines drug derivatives highlights protocol.

Language: Английский

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The Rational Design of Reducing Organophotoredox Catalysts Unlocks Proton-Coupled Electron-Transfer and Atom Transfer Radical Polymerization Mechanisms

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(3), P. 1835 - 1846

Published: Jan. 6, 2023

Photocatalysis has become a prominent tool in the arsenal of organic chemists to develop and (re)imagine transformations. However, only handful versatile photocatalysts (PCs) are available, hampering discovery new reactivities. Here, we report design complete physicochemical characterization 9-aryl dihydroacridines (9ADA) 12-aryl dihydrobenzoacridines (12ADBA) as strong reducing PCs. Punctual structural variations modulate their molecular orbital distributions unlock locally or charge-transfer (CT) excited states. The PCs presenting state showed better performances photoredox defunctionalization processes (yields up 92%), whereas featuring CT produced promising results atom transfer radical polymerization under visible light (up 1.21 Đ, 98% I*). Unlike all PC classes reported so far, 9ADA 12ADBA feature free NH group that enables catalytic multisite proton-coupled electron (MS-PCET) mechanism. This manifold allows reduction redox-inert substrates including aryl, alkyl halides, azides, phosphate ammonium salts (Ered -2.83 vs SCE) single-photon excitation. We anticipate these will open mechanistic manifolds field photocatalysis by allowing access previously inaccessible intermediates one-photon

Language: Английский

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Dual Catalysis in Organic Synthesis: Current Challenges and New Trends

European Journal of Organic Chemistry, Journal Year: 2022, Volume and Issue: 26(1)

Published: Dec. 9, 2022

Abstract Dual catalysis is one of the most powerful strategies for development chemical reactions in organic synthesis. This strategy can be divided into cooperative catalysis, relay and sequential according to actual mode operation communication between catalysts. In recent years, such has been applied a large number studies since it advantages of: 1) increasing reactivity enabling challenging transformations; 2) offering way controlling stereoselectivity asymmetric reactions, which traditional catalytic systems; 3) catalyze stereodivergent synthesis molecules bearing or more stereocenters from same starting materials. Perspective, intends introduce reader EurJOC special collection on Catalysis , aims summarize different categories dual demonstrate their benefits constructing new bonds selective manner. Finally, current challenges trends will also presented.

Language: Английский

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Organophotocatalytic Mechanisms: Simplicity or Naïvety? Diverting Reactive Pathways by Modifications of Catalyst Structure, Redox States and Substrate Preassemblies

ChemCatChem, Journal Year: 2023, Volume and Issue: 15(11)

Published: Feb. 21, 2023

Abstract Photocatalysis is a powerful tool to assemble diverse chemical scaffolds, yet bottleneck on its further development the understanding of multitude possible pathways when practitioners rely only oversimplified thermodynamic and optical factors. Recently, there growing number studies in field that exploit, inter alia , kinetic parameters organophotocatalysts are synthetically more programmable terms their redox states opportunities for aggregation with target substrate. Non‐covalent interactions play key role enables access new generation reactivities such as those open‐shell organophotocatalysts. In this review, we discuss how targeted structural modifications influence organophotocatalytic mechanisms together underlying principles. We also highlight benefits strategies preassembly static quenching overcome common reactivity issues (e. g., diffusion rate limits energetic limits).

Language: Английский

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Acridinium Salts and Cyanoarenes as Powerful Photocatalysts: Opportunities in Organic Synthesis

Angewandte Chemie, Journal Year: 2021, Volume and Issue: 133(36), P. 19678 - 19701

Published: April 22, 2021

Abstract The use of organic photocatalysts has revolutionized the field photoredox catalysis, as it allows access to reactivities that were traditionally restricted transition‐metal photocatalysts. This Minireview reports recent developments in acridinium ions and cyanoarene derivatives synthesis. activation inert chemical bonds well late‐stage functionalization biorelevant molecules are discussed, with a special focus on their mechanistic aspects.

Language: Английский

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Metal‐Free Visible‐Light Synthesis of Arylsulfonyl Fluorides: Scope and Mechanism

Chemistry - A European Journal, Journal Year: 2021, Volume and Issue: 27(34), P. 8704 - 8708

Published: April 7, 2021

Abstract The first metal‐free procedure for the synthesis of arylsulfonyl fluorides is reported. Under organo‐photoredox conditions, aryl diazonium salts react with a readily available SO 2 source (DABSO) to afford desired product through simple nucleophilic fluorination. reaction tolerates presence both electron‐rich and ‐poor aryls demonstrated broad functional group tolerance. To shed light on mechanism, several experimental techniques were combined, including fluorescence, NMR, EPR spectroscopy as well DFT calculations.

Language: Английский

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Radical α-Trifluoromethoxylation of Ketones under Batch and Flow Conditions by Means of Organic Photoredox Catalysis

Organic Letters, Journal Year: 2021, Volume and Issue: 23(18), P. 7088 - 7093

Published: Sept. 1, 2021

The first light-driven method for the α-trifluoromethoxylation of ketones is reported. Enol carbonates react with N-trifluoromethoxy-4-cyano-pyridinium, using photoredox catalyst 4-CzIPN under 456 nm irradiation, affording α-trifluoromethoxy in ≤50% isolated yield and complete chemoselectivity. As shown by 29 examples, reaction general proceeds very rapidly batch (1 h) flow conditions (2 min). Diverse product manipulations demonstrate synthetic potential disclosed accessing elusive trifluoromethoxylated bioactive ingredients.

Language: Английский

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Tailoring the Reactivity of the Langlois Reagent and Styrenes with Cyanoarenes Organophotocatalysts under Visible‐Light

Advanced Synthesis & Catalysis, Journal Year: 2021, Volume and Issue: 364(1), P. 139 - 148

Published: Sept. 25, 2021

Abstract The selective one‐step access to fluoroalkylated hexestrol derivatives, nonsteroidal estrogens, is achieved in good excellent isolated yields under organophotoredox conditions by using the stable and easy handle Langlois reagent. Furthermore, challenging hydrotrifluoromethylation of styrenes proceeds mild reaction without requirement for any additive. We assume that solvent drives pathway towards either reduction or dimerization radical intermediate generated after initial addition fluoroalkyl styrene. versatility developed system also extended encompass radical‐radical cross‐coupling as exemplified here cyanopyridine. Mechanistic investigations including luminescence EPR spectroscopy allow shed light on different mechanisms. magnified image

Language: Английский

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