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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Enantioconvergent Cu-Catalyzed Radical C–N Coupling of Racemic Secondary Alkyl Halides to Access α-Chiral Primary Amines

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(37), P. 15413 - 15419

Published: Sept. 10, 2021

α-Chiral alkyl primary amines are virtually universal synthetic precursors for all other α-chiral N-containing compounds ubiquitous in biological, pharmaceutical, and material sciences. The enantioselective amination of common halides with ammonia is appealing potential rapid access to amines, but has hitherto remained rare due the multifaceted difficulties using underdeveloped C(sp3)-N coupling. Here we demonstrate sulfoximines as excellent surrogates enantioconvergent radical C-N coupling diverse racemic secondary (>60 examples) by copper catalysis under mild thermal conditions. reaction efficiently provides highly enantioenriched N-alkyl (up 99% yield >99% ee) featuring benzyl, propargyl, α-carbonyl alkyl, α-cyano stereocenters. In addition, have converted masked thus obtained various building blocks, ligands, drugs possessing N-functionalities, such carbamate, carboxylamide, tertiary amine, oxazoline, commonly seen α-substitution patterns. These results shine light on cross-coupling a general chiral carbon-heteroatom formation strategy.

Language: Английский

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Urea group-directed organocatalytic asymmetric versatile dihalogenation of alkenes and alkynes

Nature Catalysis, Journal Year: 2021, Volume and Issue: 4(8), P. 692 - 702

Published: Aug. 9, 2021

Language: Английский

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Visible-light-driven reversible shuttle vicinal dihalogenation using lead halide perovskite quantum dot catalysts

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: Aug. 4, 2023

Abstract Dihalogenation of alkenes to the high-added value vicinal dihalides is a prominent process in modern synthetic chemistry. However, their effective conversion still requires use expensive and hazardous agents, sacrificial half-reaction coupling or primary energy input. Here, we show photocatalytically assisted shuttle (p-shuttle) strategy for redox-neutral reversible dihalogenation using low-cost stable 1,2-dihaloethane under visible light illumination. Energetic hot electrons from metal-halide perovskite QDs enable challenging photocatalytic reactions. Ultrafast laser transient absorption spectroscopy have unveiled matching with high reduction potential 1,2-dihaloethane, via two consecutive photoexcitation process. Powered by sustainable as only input, our new catalytic system dibromination, dichlorination even unexplored hetero-dihalogenation, shows good tolerance wide range at room temperature. In contrast homogeneous photocatalysts, chalcogenide other semiconductor catalysts, deliver previously unattainable performance photoredox turnover number over 120,000. This work provides opportunities visible-light-driven heterogeneous catalysis unlocking novel chemical transformations.

Language: Английский

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Enantioselective anti-Dihalogenation of Electron-Deficient Olefin: A Triplet Halo-Radical Pylon Intermediate

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(8), P. 4808 - 4818

Published: Feb. 16, 2023

The textbook alkene halogenation reaction establishes straightforward access to vicinal dihaloalkanes. However, a robust catalytic method for dihalogenizing electron-deficient olefins in an enantioselective manner is still under development, and its mechanism remains controversial. Herein, we disclose efficient regio-, anti-diastereo-, dibromination, bromochlorination, dichlorination reactions of enones catalyzed by chiral N,N'-dioxide/Yb(OTf)3 complex. With the combination electrophilic halogen halide salts as halogenating agents, array homo- heterodihalogenated derivatives achieved moderate good enantioselectivities. Moreover, DFT calculations reveal that novel triplet halo-radical pylon intermediate probable accounting exclusive regio- anti-diastereoselectivity.

Language: Английский

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Catalytic Chemo-, Regio-, Diastereo-, and Enantioselective Bromochlorination of Unsaturated Systems Enabled by Lewis Base-Controlled Chloride Release

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(29), P. 13294 - 13301

Published: July 12, 2022

A new strategy is described for the Lewis base-catalyzed bromochlorination of unsaturated systems that mechanistically distinct from prior methodologies. The novelty this method hinges on utilization thionyl chloride as a latent source in combination with little 1 mol % triphenylphosphine or oxide basic activators. This metal-free, catalytic chemo-, regio-, and diastereoselective alkenes alkynes exhibits excellent site selectivity polyunsaturated provides access to wide variety vicinal bromochlorides up >20:1 regio- diastereoselectivity. precision installation Br, Cl, I various combinations also demonstrated by simply varying commercial halogenating reagents employed. Notably, when chiral base promoter employed, an enantioselective chalcones possible 92:8 enantiomeric ratio utilizing only 1-3 (DHQD)2PHAL.

Language: Английский

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Lewis Base-Catalyzed Interhalogenation of Terminal Allenes: Selective Strategy for Accessing Vicinal Vinylic, Allylic Heterodihalides

Organic Letters, Journal Year: 2025, Volume and Issue: unknown

Published: March 28, 2025

Though precedent remains limited, the selective interhalogenation of allenes offers a valuable synthetic strategy to access products where each halide exhibits orthogonal reactivity. Here, we describe Lewis base-catalyzed approach for dihalogenation (bromochlorination, iodochlorination, iodobromination, and dibromination) terminal allenes. By employing just 1 mol % triphenylphosphine oxide or hexamethylphosphoramide activate thionyl halides in presence electrophilic halogenation reagents, achieve conversion monosubstituted vicinal allylic, vinylic dihalides with up 93% yield >20:1 regioisomeric ratio, favoring branched dihalogenated product. A range functional groups is tolerated, including nitrile, ester, phosphate, sulfonamide, silyl groups, reaction proved be scalable. The utility various dihalide was investigated substitution cross-coupling chemistry, highlighting distinct reactivity among different classes.

Language: Английский

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Enantioselective Cu-Catalyzed Nucleophilic Addition of Fluorinated Reagents: C–C Bond Formation for the Synthesis of Chiral Vicinal Difluorides

Organic Letters, Journal Year: 2022, Volume and Issue: 24(11), P. 2197 - 2202

Published: March 14, 2022

Herein we described the first enantioselective Cu/sulfoxide phosphine (SOP) complex catalyzed nucleophilic addition of fluorinated enolates to gem-difluoroalkenes. The enantioenriched vicinal difluorides, containing a chiral tertiary fluoride and fluoroalkene, were successfully afforded via C–C bond formation in good yields (up 94% yield), high Z/E-selectivity (5:1 → 50:1 for Z-isomer), excellent enantioselectivities 98.5:1.5 er). Utility this approach was demonstrated by modification biologically active compounds.

Language: Английский

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Diastereodivergent nucleophile–nucleophile alkene chlorofluorination

Nature Chemistry, Journal Year: 2024, Volume and Issue: 16(10), P. 1647 - 1655

Published: July 1, 2024

The selective hetero-dihalogenation of alkenes provides useful building blocks for a broad range chemical applications. Unlike homo-dihalogenation, reactions, especially fluorohalogenation, are underdeveloped. Current approaches combine an electrophilic halogen source with nucleophilic source, which necessarily leads to anti-addition, and regioselectivity has only been achieved using highly activated alkenes. Here we describe alternative, nucleophile-nucleophile approach that adds chloride fluoride ions over unactivated in regio-, chemo- diastereoselective manner. A curious switch the reaction mechanism was discovered, triggers complete reversal diastereoselectivity promote either anti- or syn-addition. conditions demonstrated on array pharmaceutically relevant compounds, detailed mechanistic studies reveal selectivity between syn- anti-diastereomers based different active iodanes two halides first.

Language: Английский

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The applications of catalytic asymmetric halocyclization in natural product synthesis

Organic Chemistry Frontiers, Journal Year: 2021, Volume and Issue: 9(2), P. 499 - 516

Published: Nov. 18, 2021

Catalytic asymmetric halocyclization of olefinic substrate has evolved rapidly and been well utilized as a practical strategy for constructing enantioenriched cyclic skeletons in natural product synthesis.

Language: Английский

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