Photons or Electrons? A Critical Comparison of Electrochemistry and Photoredox Catalysis for Organic Synthesis

Chemical Reviews, Journal Year: 2021, Volume and Issue: 122(2), P. 2487 - 2649

Published: Nov. 9, 2021

Redox processes are at the heart of synthetic methods that rely on either electrochemistry or photoredox catalysis, but how do and catalysis compare? Both approaches provide access to high energy intermediates (e.g., radicals) enable bond formations not constrained by rules ionic 2 electron (e) mechanisms. Instead, they 1e mechanisms capable bypassing electronic steric limitations protecting group requirements, thus enabling chemists disconnect molecules in new different ways. However, while providing similar intermediates, differ several physical chemistry principles. Understanding those differences can be key designing transformations forging disconnections. This review aims highlight these similarities between comparing their underlying principles describing impact electrochemical photochemical methods.

Language: Английский

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Transition Metal-Catalyzed Organic Reactions under Visible Light: Recent Developments and Future Perspectives

ACS Catalysis, Journal Year: 2020, Volume and Issue: 10(16), P. 9170 - 9196

Published: July 20, 2020

The development of transition metal (TM) catalysis for organic synthesis under visible light without recourse to typical photoredox catalysts has become a rapidly growing area research and been actively explored in the past several years. Distinct from extensively developed catalysis, which photocatalyst generally does not directly participate bond-forming process, photocatalyst/TM synergistic absorbs photon energy transfers TM catalyst through redox or transfer this Review focuses on summarizing recent developments photocatalytic reactions that use complexes both absorb catalytic bond formation involving covalently bonded intermediate. contents are categorized by used (Pd, Cu, Co, Ni, Mn, Au, Rh, Fe, Ru), with descending sequence according number examples reported each metal, provide an overview April 2020. Future perspectives personal opinions regarding expanding field also discussed.

Language: Английский

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Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

Chemical Reviews, Journal Year: 2021, Volume and Issue: 122(2), P. 2650 - 2694

Published: Aug. 27, 2021

Geometrical E → Z alkene isomerization is intimately entwined in the historical fabric of organic photochemistry and enjoying a renaissance (Roth et al. Angew. Chem., Int. Ed. Engl. 1989 28, 1193–1207). This consequence fundamental stereochemical importance Z-alkenes, juxtaposed with frustrations thermal reactivity that are rooted microscopic reversibility. Accessing excited state paradigms allow this latter obstacle to be circumnavigated by exploiting subtle differences photophysical behavior substrate product chromophores: provides molecular basis for directionality. While direct irradiation operationally simple, photosensitization via selective energy transfer enables augmentation repertoire include substrates not directly photons. Through sustained innovation, an impressive portfolio tailored small molecule catalysts range triplet energies now widely available facilitate contra-thermodynamic thermo-neutral reactions generate Z-alkene fragments. review intended serve as practical guide covering geometric alkenes enabled catalysis from 2000 2020, logical sequel excellent treatment Dugave Demange (Chem. Rev. 2003 103, 2475–2532). The mechanistic foundations underpinning selectivity discussed together induction models rationales explain counterintuitive directionality these processes which very distinguish product. Implications subsequent stereospecific transformations, application total synthesis, regioselective polyene isomerization, spatiotemporal control pre-existing configuration broader sense discussed.

Language: Английский

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Visible‐Light‐Induced Homolysis of Earth‐Abundant Metal‐Substrate Complexes: A Complementary Activation Strategy in Photoredox Catalysis

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(39), P. 21100 - 21115

Published: Feb. 18, 2021

Abstract The mainstream applications of visible‐light photoredox catalysis predominately involve outer‐sphere single‐electron transfer (SET) or energy (EnT) processes precious metal Ru II Ir III complexes organic dyes with low photostability. Earth‐abundant metal‐based M n L ‐type (M=metal, =polydentate ligands) are rapidly evolving as alternative photocatalysts they offer not only economic and ecological advantages but also access to the complementary inner‐sphere mechanistic modes, thereby transcending their inherent limitations ultrashort excited‐state lifetimes for use effective photocatalysts. generic process, termed visible‐light‐induced homolysis (VLIH), entails formation suitable light‐absorbing ligated metal–substrate (M ‐Z; Z=substrate) that can undergo homolytic cleavage generate n−1 Z . further transformations.

Language: Английский

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Enantioselective Radical Reactions Using Chiral Catalysts

Chemical Reviews, Journal Year: 2022, Volume and Issue: 122(6), P. 5842 - 5976

Published: Jan. 24, 2022

Benefiting from the impressive increase in fundamental knowledge, last 20 years have shown a continuous burst of new ideas and consequently plethora catalytic methods for enantioselective radical reactions. This review aims to provide complete survey progress achieved over this latter period. The first part focuses on use chiral organocatalysts, these include catalysts covalently linked substrate those that interact with by weaker interactions like hydrogen bonds. second is devoted transition-metal redox catalysis which organized according increasing atomic number first-row transition metals (Ti, Cr, Fe, Mn, Co, Ni, Cu). Bioinspired manganese- iron-mediated hydroxylations oxidations are also discussed. A specific section dedicated reactivity Ru, Rh, Ir complexes as Lewis acids special focus at metal. Absorption photons result different events such energy transfer, single-electron hydrogen-atom transfer facilitating formation radicals. Organocatalysis has been successfully combined photocatalysts, opened pathways enlarging precursors available. merger photocatalysis organo- or metalla-photocatalysis brought novelty allowed discovery large original transformations. enzyme-catalyzed reactions involving intermediates largely benefit visible-light irradiation included review. provides comprehensive inventory goal detailing reaction mechanisms involved transformations any nonspecialist could find their own creativity invent yet unknown applications.

Language: Английский

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Catalytic three-component dicarbofunctionalization reactions involving radical capture by nickel

Chemical Society Reviews, Journal Year: 2021, Volume and Issue: 50(19), P. 10836 - 10856

Published: Jan. 1, 2021

The catalytic dicarbofunctionalization of unsaturated π bonds represents a powerful platform for the rapid construction complex motifs. Despite remarkable progress, novel and efficient methods achieving such transformations under milder conditions with chemo-, regio-, stereoselectivity still remain significant challenge; thus, their development is highly desirable. Recently, merging nickel catalysis radical chemistry offers new benign unprecedented reactivity selectivity. In this review, we summarize recent advances in area by underpinning domino involving capture to provide clear overview reaction designs mechanistic scenarios.

Language: Английский

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Developments in Photoredox/Nickel Dual-Catalyzed 1,2-Difunctionalizations

Chem, Journal Year: 2020, Volume and Issue: 6(6), P. 1327 - 1339

Published: June 1, 2020

Language: Английский

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Nickel‐Catalyzed C‐Heteroatom Cross‐Coupling Reactions under Mild Conditions via Facilitated Reductive Elimination

Angewandte Chemie International Edition, Journal Year: 2020, Volume and Issue: 60(33), P. 17810 - 17831

Published: Nov. 30, 2020

The formation of C-heteroatom bonds represents an important type bond-forming reaction in organic synthesis and often provides a fast efficient access to privileged structures found pharmaceuticals, agrochemical materials. In contrast conventional Pd- or Cu-catalyzed cross-couplings under high-temperature conditions, recent advances homo- heterogeneous Ni-catalyzed formations mild conditions are particularly attractive from the standpoint sustainability practicability. generation NiIII excited NiII intermediates facilitate reductive elimination step achieve cross-couplings. This review overview state-of-the-art approaches for bond highlights developments photoredox nickel dual catalysis involving SET energy transfer processes; photoexcited catalysis; electro graphitic carbon nitride (mpg-CN), metal frameworks (MOFs) semiconductor quantum dots (QDs); as well more zinc catalyzed reactions.

Language: Английский

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General Method for Enantioselective Three-Component Carboarylation of Alkenes Enabled by Visible-Light Dual Photoredox/Nickel Catalysis

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(48), P. 20390 - 20399

Published: Nov. 19, 2020

A visible-light-promoted photoredox/nickel protocol for the enantioselective three-component carboarylation of alkenes with tertiary and secondary alkyltrifluoroborates aryl bromides is described. This redox-neutral allows facile divergent access to a wide array enantioenriched β-alkyl-α-arylated carbonyls, phosphonates, sulfones in high yields excellent enantioselectivities from readily available starting materials. We also report modular synthesis flurbiprofen analogs piragliatin lead compound demonstrate synthetic utility. Experimental computational mechanistic studies were performed gain insights into mechanism origin chemo- enantioselectivity.

Language: Английский

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Nickel-catalyzed formation of quaternary carbon centers using tertiary alkyl electrophiles

Chemical Society Reviews, Journal Year: 2021, Volume and Issue: 50(6), P. 4162 - 4184

Published: Jan. 1, 2021

This review provides a comprehensive summary of recent advances in nickel-catalyzed reactions employing tertiary alkyl electrophiles for the construction quaternary carbon centers.

Language: Английский

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