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

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Nitrogen-Centered Radicals in Functionalization of sp² Systems: Generation, Reactivity, and Applications in Synthesis

Chemical Reviews, Journal Year: 2022, Volume and Issue: 122(9), P. 8181 - 8260

Published: March 14, 2022

The chemistry of nitrogen-centered radicals (NCRs) has plentiful applications in organic synthesis, and they continue to expand as our understanding these reactive species increases. utility intermediates is demonstrated the recent advances C–H amination (di)amination alkenes. Synthesis previously challenging structures can be achieved by efficient functionalization sp2 moieties without prefunctionalization, allowing for faster more streamlined synthesis. This Review addresses generation, reactivity, application NCRs, including, but not limited to, iminyl, aminyl, amidyl, aminium species. Contributions from early discovery up most examples have been highlighted, covering radical initiation, thermolysis, photolysis, and, recently, photoredox catalysis. Radical-mediated intermolecular (hetero)arenes occur with a variety complex amine precursors, generating aniline derivatives, an important class drug development. Functionalization olefins achievable high anti-Markovnikov regioselectivity allows access difunctionalized when intermediate carbon are trapped. Additionally, reactivity NCRs harnessed rapid construction N-heterocycles such pyrrolidines, phenanthridines, quinoxalines, quinazolinones.

Language: Английский

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Thioxanthone: a powerful photocatalyst for organic reactions

Organic & Biomolecular Chemistry, Journal Year: 2021, Volume and Issue: 19(24), P. 5237 - 5253

Published: Jan. 1, 2021

Photoorganocatalysis has been recognised by the organic chemistry community as an important part of photochemistry and catalysis. In general, aromatic ketones constitute key players in this type catalysis they are involved a plethora examples literature. Among various ketones, thioxanthone (TX) seems to play unique role photochemistry. comparison with other TX high triplet energy relatively long lifetime, while it ability participate successfully merger reactions metal complexes. review, we will discuss photophysical properties small molecule, well numerous photochemical reactions, where is employed mediator more specifically polymerisation transformations.

Language: Английский

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Photoinduced Copper-Catalyzed Asymmetric C–O Cross-Coupling

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(33), P. 13382 - 13392

Published: Aug. 10, 2021

The construction of carbon–heteroatom bonds is one the most active areas research in organic chemistry because function molecules often derived from presence heteroatoms. Although considerable advances have recently been achieved radical-involved catalytic asymmetric C–N bond formation, there has little progress corresponding C–O bond-forming processes. Here, we describe a photoinduced copper-catalyzed cross-coupling readily available oxime esters and 1,3-dienes to generate diversely substituted allylic with high regio- enantioselectivity (>75 examples; up 95% ee). reaction proceeds at room temperature under excitation by purple light-emitting diodes (LEDs) features use single, earth-abundant copper-based chiral catalyst as both photoredox for radical generation source induction coupling. Combined experimental density functional theory (DFT) computational studies suggest formation π-allylcopper complexes redox-active bifunctional reagents through radical–polar crossover process.

Language: Английский

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Energy transfer photocatalysis: exciting modes of reactivity

Chemical Society Reviews, Journal Year: 2024, Volume and Issue: 53(3), P. 1068 - 1089

Published: Jan. 1, 2024

Leveraging light energy to expose the ‘dark’ reactive states describes whole essence of triplet–triplet transfer. This offers an impressive opportunity conduct a multitude diverse reactions and access sought-after molecular motifs.

Language: Английский

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Photochemical single-step synthesis of β-amino acid derivatives from alkenes and (hetero)arenes

Nature Chemistry, Journal Year: 2022, Volume and Issue: 14(10), P. 1174 - 1184

Published: Aug. 1, 2022

Language: Английский

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Reactivity of oximes for diverse methodologies and synthetic applications

Nature Synthesis, Journal Year: 2022, Volume and Issue: 1(1), P. 24 - 36

Published: Jan. 12, 2022

Language: Английский

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The promise and pitfalls of photocatalysis for organic synthesis

Chem Catalysis, Journal Year: 2022, Volume and Issue: 2(3), P. 468 - 476

Published: Feb. 3, 2022

Language: Английский

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EnT-Mediated N–S Bond Homolysis of a Bifunctional Reagent Leading to Aliphatic Sulfonyl Fluorides

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(4), P. 2364 - 2374

Published: Jan. 18, 2023

Sulfur(VI) fluoride exchange (SuFEx) gives rise to a plethora of high-valent sulfur linkages; however, the availability (aliphatic) sulfonyl manifolds lag behind, owing limited sources introducing SO2F moiety via classical two-electron approach. Recently, radical-based methodologies have emerged as complementary strategy increase diversity accessible click partners. In this work, synthesis bench-stable sulfamoyl reagent is presented, which may undergo sigma-bond homolysis upon visible-light-induced sensitization form protected β-amino fluorides from alkene feedstocks. Notably, offers an appealing access various building blocks for peptido fluorides, relevant in medicinal chemistry context, well intriguing entry β-ammonium sulfonates and β-sultams, alkenes. Densely functionalized 1,3-sultones were obtained by employing allyl alcohols substrates. Surprisingly, chloride-derived β-imino underwent S-O bond formation ring closure yield rigid cyclopropyl sulfonate ester under SuFEx conditions. Furthermore, engaging thiol-based hydrogen atom donor reaction, reactivity same can be tuned toward direct aliphatic fluorides. Mechanistic experiments indicate energy transfer (EnT)-mediated process. The transient radical adds product occurs either radical-radical coupling or (HAT), respectively.

Language: Английский

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N–O Bond Activation by Energy Transfer Photocatalysis

Accounts of Chemical Research, Journal Year: 2022, Volume and Issue: 55(17), P. 2526 - 2541

Published: Aug. 20, 2022

ConspectusA radical shift toward energy transfer photocatalysis from electron under visible-light photoirradiation is often due to the greener prospects of atom and process economy. Recent advances in embrace unique strategies for direct small-molecule activation sometimes extraordinary chemical bond formation absence additional/sacrificial reagents. Selective requires careful selection substrates photocatalysts a perfect match with respect their triplet energies while having incompatible redox potentials prevent competitive pathways. Substrates containing labile N–O bonds are potential targets generating reactive key intermediates via access variety functionalized molecules. Typically, differential densities N O heteroatoms have been exploited generation either N- or O-centered by pathway. However, latest developments involve homolysis generate both radicals subsequent utilization diverse organic transformations, also sacrificial In this Account, we highlight our contributions field intermediates, coverage useful mechanistic insights. More specifically, well-designed bond-containing such as 1,2,4-oxadiazolines, oxime esters, N-indolyl carbonates, N-enoxybenzotriazoles were successfully utilized versatile transformations involving selective over high state energy. Direct N-, O-, C-centered (if decarboxylation follows) was achieved cross-couplings rearrangement processes. particular, open-shell nitrogen including N(sp2) N(sp3) nitrenes, utilized. Notably, diversified identical through control reaction conditions. 1,2,4-Oxadiazolines converted into spiro-azolactams iminyl presence 1O2, benzimidazoles, sulfoximines external sulfoxide reagent nitrene inert Besides, esters underwent intramolecular C(sp3)–N radical–radical coupling intermolecular combined transfer–hydrogen strategy. Furthermore, series electrochemical photophysical experiments well computational studies performed substantiate proposed energy-transfer-driven We hope that Account will serve guide rational design processes further bonds.

Language: Английский

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