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

---

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

Chemical Reviews, Journal Year: 2021, Volume and Issue: 122(2), P. 2017 - 2291

Published: Nov. 23, 2021

We present here a review of the photochemical and electrochemical applications multi-site proton-coupled electron transfer (MS-PCET) in organic synthesis. MS-PCETs are redox mechanisms which both an proton exchanged together, often concerted elementary step. As such, MS-PCET can function as non-classical mechanism for homolytic bond activation, providing opportunities to generate synthetically useful free radical intermediates directly from wide variety common functional groups. introduction practitioner’s guide reaction design, with emphasis on unique energetic selectivity features that characteristic this class. then chapters oxidative N–H, O–H, S–H, C–H homolysis methods, generation corresponding neutral species. Then, reductive PCET activations involving carbonyl, imine, other X═Y π-systems, heteroarenes, where ketyl, α-amino, heteroarene-derived radicals be generated. Finally, we asymmetric catalysis materials device applications. Within each chapter, subdivide by group undergoing homolysis, thereafter type transformation being promoted. Methods published prior end December 2020 presented.

Language: Английский

---

Photocatalytic Late-Stage C–H Functionalization

Chemical Reviews, Journal Year: 2023, Volume and Issue: 123(8), P. 4237 - 4352

Published: Jan. 24, 2023

The emergence of modern photocatalysis, characterized by mildness and selectivity, has significantly spurred innovative late-stage C–H functionalization approaches that make use low energy photons as a controllable source. Compared to traditional strategies, photocatalysis paves the way toward complementary and/or previously unattainable regio- chemoselectivities. Merging compelling benefits with workflow offers potentially unmatched arsenal tackle drug development campaigns beyond. This Review highlights photocatalytic strategies small-molecule drugs, agrochemicals, natural products, classified according targeted bond newly formed one. Emphasis is devoted identifying, describing, comparing main mechanistic scenarios. draws critical comparison between established ionic chemistry photocatalyzed radical-based manifolds. aims establish current state-of-the-art illustrate key unsolved challenges be addressed in future. authors aim introduce general readership functionalization, specialist practitioners evaluation methodologies, potential for improvement, future uncharted directions.

Language: Английский

---

Recent advances in N-heterocyclic carbene-based radical catalysis

Chemical Science, Journal Year: 2020, Volume and Issue: 11(22), P. 5630 - 5636

Published: Jan. 1, 2020

This minireview examines the history and state-of-the-art of N-heterocyclic carbene-based radical catalysis.

Language: Английский

---

Photocatalysis in the Life Science Industry

Chemical Reviews, Journal Year: 2021, Volume and Issue: 122(2), P. 2907 - 2980

Published: Sept. 24, 2021

In the pursuit of new pharmaceuticals and agrochemicals, chemists in life science industry require access to mild robust synthetic methodologies systematically modify chemical structures, explore novel space, enable efficient synthesis. this context, photocatalysis has emerged as a powerful technology for synthesis complex often highly functionalized molecules. This Review aims summarize published contributions field from industry, including research industrial-academic partnerships. An overview developed strategic applications synthesis, peptide functionalization, isotope labeling, both DNA-encoded traditional library is provided, along with summary state-of-the-art photoreactor effective upscaling photocatalytic reactions.

Language: Английский

---

Radical philicity and its role in selective organic transformations

Nature Reviews Chemistry, Journal Year: 2021, Volume and Issue: 5(7), P. 486 - 499

Published: June 22, 2021

Language: Английский

---

Light in Gold Catalysis

Chemical Reviews, Journal Year: 2021, Volume and Issue: 121(14), P. 8868 - 8925

Published: Jan. 25, 2021

Within the wide family of gold-catalyzed reactions, gold photocatalysis intrinsically features unique elementary steps. When catalysis meets photocatalysis, a valence change center can easily be achieved via electron transfer and radical addition, avoiding use stoichiometric sacrificial external oxidants. The excellent compatibility radicals with catalysts opens door to series important organic transformations, including redox-neutral C–C C–X coupling, C–H activation, formal radical–radical cross-coupling. complexes nicely complements existing photoredox strategies also new avenue for chemistry. This review covers transformations both mononuclear gold(I) (with without photosensitizer) dinuclear photocatalysts. Various fascinating methodologies, their value chemists, current mechanistic understanding are discussed. most recent examples demonstrate feasibility both, participate in excited state energy (EnT), rather than transfer. rare applications gold(III) photocatalysts, homogeneous heterogeneous, summarized.

Language: Английский

---

N-Heterocyclic Carbene-Based Catalysis Enabling Cross-Coupling Reactions

ACS Catalysis, Journal Year: 2020, Volume and Issue: 10(12), P. 6862 - 6869

Published: June 8, 2020

N-Heterocyclic carbene (NHC) organocatalysis to promote so-called umpolung reactions has emerged as a powerful tool for modern organic synthesis. NHC-bound nucleophiles known Breslow intermediates can be obtained by reacting an NHC catalyst with aldehyde and will add carbon–heteroatom or carbon–carbon double bonds. On the other hand, substitution-type cross-couplings of carbon electrophiles (that is, R–X species) generate bonds have also been demonstrated even though such processes are difficult less mature at present. This Perspective briefly summarizes NHC-based catalysis enabling cross-coupling reactions. Three types systems examined: anionic, hybrid, radical catalysis.

Language: Английский

---

Strategies to Generate Nitrogen-centered Radicals That May Rely on Photoredox Catalysis: Development in Reaction Methodology and Applications in Organic Synthesis

Chemical Reviews, Journal Year: 2021, Volume and Issue: 122(2), P. 2353 - 2428

Published: Oct. 8, 2021

For more than 70 years, nitrogen-centered radicals have been recognized as potent synthetic intermediates. This review is a survey designed for use by chemists engaged in target-oriented synthesis. summarizes the recent paradigm shift access to and application of N-centered enabled visible-light photocatalysis. broadens streamlines approaches many small molecules because photocatalysis conditions are mild. Explicit attention paid innovative advances N–X bonds radical precursors, where X = Cl, N, S, O, H. clarity, key mechanistic data noted, available. Synthetic applications limitations summarized illuminate tremendous utility photocatalytically generated radicals.

Language: Английский

---

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

---