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

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Enantioselective Photochemical Reactions Enabled by Triplet Energy Transfer

Chemical Reviews, Journal Year: 2021, Volume and Issue: 122(2), P. 1626 - 1653

Published: July 6, 2021

For molecules with a singlet ground state, the population of triplet states is mainly possible (a) by direct excitation and subsequent intersystem crossing or (b) energy transfer from an appropriate sensitizer. The latter scenario enables catalytic photochemical reaction in which sensitizer adopts role catalyst undergoing several cycles photon absorption to substrate. If product molecule triplet-sensitized process chiral, this can proceed enantioselectively upon judicious choice chiral An enantioselective also occur dual approach which, apart achiral sensitizer, second activates substrate toward sensitization. Although idea reactions via intermediates has been pursued for more than 50 years, notable selectivities exceeding 90% enantiomeric excess (ee) have only realized past decade. This review attempts provide comprehensive survey on various were rendered

Language: Английский

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Radical NHC Catalysis

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(19), P. 11984 - 11999

Published: Sept. 19, 2022

Radical/radical cross-coupling reactions represent an efficient and straightforward approach for the construction of chemical bonds accordingly have drawn increasing attention over past decades. In order to achieve synthetically useful transformations, a persistent radical should be coupled with transient in accordance effect (PRE). However, known radicals outnumber by far types free radicals, which limits widespread application PRE, until today. Thus, development between has been focus, meanwhile transition-metal catalysis successfully implemented artificially prolong lifetimes, allowing their utilization formal radical/radical cross-couplings. Complementary research field recently uncovered that organocatalytically generated NHC-derived ketyl are type catalytically radicals. NHC-catalyzed transformations aldehydes carboxylic acid derivatives enabled disclosure ever-increasing number interesting reactions, different from traditional ionic processes, offering otherwise inaccessible activation modes. These discoveries opened door NHC organocatalysis manipulation reactions. Due its obvious potential synthetic organic chemistry, it is timely provide perspective on this emerging field.

Language: Английский

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Ni-electrocatalytic Csp3–Csp3 doubly decarboxylative coupling

Nature, Journal Year: 2022, Volume and Issue: 606(7913), P. 313 - 318

Published: April 5, 2022

Language: Английский

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Direct decarboxylative Giese reactions

Chemical Society Reviews, Journal Year: 2022, Volume and Issue: 51(4), P. 1415 - 1453

Published: Jan. 1, 2022

This review summarizes recent progress on using carboxylic acids directly as convenient precursors for the 1,4-radical conjugate addition (Giese) reaction.

Language: Английский

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Overcoming Limitations in Decarboxylative Arylation via Ag–Ni Electrocatalysis

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(38), P. 17709 - 17720

Published: Sept. 15, 2022

A useful protocol for achieving decarboxylative cross-coupling (DCC) of redox-active esters (RAE, isolated or generated in situ) and halo(hetero)arenes is reported. This pragmatically focused study employs a unique Ag-Ni electrocatalytic platform to overcome numerous limitations that have plagued this strategically powerful transformation. In its optimized form, coupling partners can be combined surprisingly simple way: open the air, using technical-grade solvents, an inexpensive ligand Ni source, substoichiometric AgNO3, proceeding at room temperature with commercial potentiostat. Most importantly, all results are placed into context by benchmarking state-of-the-art methods. Applications presented simplify synthesis rapidly enable access challenging chemical space. Finally, adaptation multiple scale regimes, ranging from parallel milligram-based decagram recirculating flow presented.

Language: Английский

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Decarboxylative Cross-Coupling: A Radical Tool in Medicinal Chemistry

ACS Medicinal Chemistry Letters, Journal Year: 2022, Volume and Issue: 13(9), P. 1413 - 1420

Published: Aug. 10, 2022

Carboxylic acids, the most versatile and ubiquitous diversity input used in medicinal chemistry for canonical polar bond constructions such as amide synthesis, can now be employed a fundamentally different category of reaction to make C-C bonds by harnessing power radicals. This outlook serves user-guide aid practitioners both design syntheses that leverage simplifying this disconnection precise tactics enable them. Taken together, emerging area holds potential rapidly accelerate access chemical space value modern chemistry.

Language: Английский

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Catalytic Asymmetric Construction of Axially and Centrally Chiral Heterobiaryls by Minisci Reaction

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(13), P. 6040 - 6049

Published: March 24, 2022

Axially chiral biaryls and heterobiaryls constitute the most represented subclass of atropisomers with prevalence in natural products, bioactive compounds, privileged ligand/catalysts, optically pure materials. Despite many ionic protocols for their construction, radical-based variants represent another highly desirable intriguing strategy but are far less developed. Moreover, efficient synthesis axially heterobiaryl molecules, especially ones having multiple heteroatoms other types elements, through radical routes remains extremely limited. We herein disclose first catalytic asymmetric, metal-free construction centrally by Minisci reaction 5-arylpyrimidines α-amino acid-derived redox-active esters. This is enabled use 4CzIPN as an organic photoredox catalyst conjunction a phosphoric acid catalyst. The achieved variety interesting featuring union α-branched amine generally excellent regio-, diastereo-, enantioselectivity (up to 82% yield; >19:1 dr; >99% ee). finding also builds up new platform development desymmetrization methods via radical-involved atroposelective functionalization at heteroarene prochiral heterobiaryls.

Language: Английский

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Free Carboxylic Acids: The Trend of Radical Decarboxylative Functionalization

European Journal of Organic Chemistry, Journal Year: 2023, Volume and Issue: 26(21)

Published: April 7, 2023

Abstract The exceptional versatility of carboxylic acids has been extensively exploited in organic synthesis across several decades. There a recent upsurge radical decarboxylative transformations. process can be initiated under mild conditions, and the resultant radicals have orthogonal reactivities to closed‐shell species, thus providing immense opportunities for streamlining novel reactions. use free is most desirable owing its high atom step economy. Aiming demonstrate attractiveness strategy inspire chemists tackle existing challenges, this review outlines advances on functionalization acids.

Language: Английский

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Multicomponent Synthesis of α-Branched Amines via a Zinc-Mediated Carbonyl Alkylative Amination Reaction

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(13), P. 9045 - 9062

Published: March 15, 2024

Methods for the synthesis of α-branched alkylamines are important due to their ubiquity in biologically active molecules. Despite development many methods amine preparation, C(sp3)-rich nitrogen-containing compounds continue pose challenges synthesis. While carbonyl reductive amination (CRA) between ketones and is cornerstone method alkylamine synthesis, it sometimes limited by sterically demanding condensation step dialkyl amines more restricted availability compared aldehydes. We recently reported a "higher-order" variant this transformation, alkylative (CAA), which utilized halogen atom transfer (XAT)-mediated radical mechanism, enabling streamlined complex alkylamines. efficacy visible-light-driven approach, displayed scalability issues, competitive was problem certain substrate classes, limiting applicability. Here, we report change reaction regime that expands CAA platform through realization an extremely broad zinc-mediated reaction. This new strategy enabled elimination CRA, simplified purification, improved scope. Furthermore, harnessed carboxylic acid derivatives as alkyl donors facilitated α-trialkyl tertiary amines, cannot be accessed via CRA. Zn-mediated can carried out at variety scales, from 10 μmol setup microtiter plates high-throughput experimentation, gram-scale medicinally-relevant compounds. believe transformation enables robust, efficient, economical access provides viable alternative current benchmark methods.

Language: Английский

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