Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

Chemical Reviews, Год журнала: 2021, Номер 122(2), С. 2650 - 2694

Опубликована: Авг. 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.

Язык: Английский

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Catalytic, contra-Thermodynamic Positional Alkene Isomerization

Journal of the American Chemical Society, Год журнала: 2021, Номер 144(1), С. 145 - 152

Опубликована: Дек. 30, 2021

The positional isomerization of C═C double bonds is a powerful strategy for the interconversion alkene regioisomers. However, existing methods provide access to thermodynamically more stable isomers from less starting materials. Here, we report discovery dual catalyst system that promotes contra-thermodynamic under photochemical irradiation, providing terminal directly conjugated, internal utility method demonstrated in deconjugation diverse electron-rich/electron-poor alkenes and through strategic application natural product synthesis. Mechanistic studies are consistent with regiospecific bimolecular homolytic substitution (SH2′) mechanism proceeding an allyl-cobaloxime intermediate.

Язык: Английский

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Contra-Thermodynamic Positional Isomerization of Olefins

Journal of the American Chemical Society, Год журнала: 2021, Номер 144(1), С. 137 - 144

Опубликована: Дек. 30, 2021

A light-driven method for the contra-thermodynamic positional isomerization of olefins is described. In this work, stepwise PCET activation a more substituted and thermodynamically stable olefin substrate mediated by an excited-state oxidant Brønsted base to afford allylic radical that captured Cr(II) cocatalyst furnish allylchromium(III) intermediate. situ protodemetalation allylchromium complex methanol highly regioselective affords isomerized less alkene product. The higher oxidation potential isomer renders it inert further oxidant, enabling accumulate in solution over course reaction. broad range isopropylidene substrates are accommodated, including enol ethers, enamides, styrenes, 1,3-dienes, tetrasubstituted alkyl olefins. Mechanistic investigations step also presented.

Язык: Английский

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Remote Hydroamination of Disubstituted Alkenes by a Combination of Isomerization and Regioselective N–H Addition

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(7), С. 3875 - 3881

Опубликована: Фев. 13, 2023

Remote hydrofunctionalizations of alkenes incorporate functional groups distal to existing carbon–carbon double bonds. While remote carbonylations are well-known, most common for addition relatively nonpolar B–H, Si–H, and C–H bonds with alkenes. We report a system the hydroamination disubstituted functionalize an alkyl chain selectively at subterminal, unactivated, methylene position. Critical high regioselectivity reaction rates electronic properties substituent on amine development ligand DIP-Ad-SEGPHOS by evaluating steric effects modules reactivity selectivity. The is compatible broad scope aminopyridines enables regioconvergent synthesis amines from isomeric mixture products can be derivatized nucleophilic aromatic substitution amino variety nucleophiles.

Язык: Английский

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Organic Synthesis Away from Equilibrium: Contrathermodynamic Transformations Enabled by Excited-State Electron Transfer

Accounts of Chemical Research, Год журнала: 2024, Номер 57(13), С. 1827 - 1838

Опубликована: Июнь 21, 2024

ConspectusChemists have long been inspired by biological photosynthesis, wherein a series of excited-state electron transfer (ET) events facilitate the conversion low energy starting materials such as H

Язык: Английский

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Strain-Inducing Positional Alkene Isomerization

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(36), С. 20053 - 20061

Опубликована: Авг. 30, 2023

Small, strained ring systems are important pharmacophores in medicinal chemistry and versatile intermediates organic synthesis. However, the kinetic thermodynamic instability of many molecules renders them challenging to prepare. Here, we report a strain-inducing positional alkene isomerization reaction that provides mild selective access cyclobutene building blocks from readily obtained cyclobutylidene precursors. This endergonic relies on sequential synergistic action decatungstate polyanion photocatalyst cobaloxime co-catalyst store potential energy form strain. The versatility products is demonstrated through diverse subsequent strain-releasing transformations. Mechanistic studies reveal steric basis for strain-selective product formation.

Язык: Английский

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Iron‐Catalyzed Positional and Geometrical Isomerization of Alkenes

Advanced Synthesis & Catalysis, Год журнала: 2023, Номер 365(8), С. 1100 - 1111

Опубликована: Фев. 20, 2023

Abstract This review outlines the most noteworthy achievements of last few years in renascent field positional and geometrical isomerization alkenes using iron catalysis, from a mechanistic perspective. Particular attention will be placed on developments beyond seminal contributions carbonyl complexes their aspects underlying nature active species. The relevant literature has been covered until late 2022. magnified image

Язык: Английский

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Photoinduced Pd‐Catalyzed Direct Sulfonylation of Allylic C–H Bonds

Angewandte Chemie International Edition, Год журнала: 2024, Номер 64(1)

Опубликована: Сен. 17, 2024

Allylic sulfones are valuable motifs due to their medicinal and biological significance versatile chemical reactivities. While direct allylic C-H sulfonylation represents a straightforward desirable approach, these methods primarily restricted terminal alkenes, leaving the engagement of internal counterparts formidable challenge. Herein we report photocatalytic approach that accommodates both cyclic acyclic alkenes with diverse substitution patterns electronic properties. Importantly, obtained can be readily diversified into wide range products, thus enabling formal alkene transposition all-carbon quaternary center formation through sequential functionalization.

Язык: Английский

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Asymmetric Hydroacylation Involving Alkene Isomerization for the Construction of C₃‐Chirogenic Center

Angewandte Chemie International Edition, Год журнала: 2021, Номер 60(16), С. 8997 - 9002

Опубликована: Янв. 28, 2021

Abstract A new transformation pattern for enantioselective intramolecular hydroacylation has been developed involving an alkene isomerization strategy. Proceeding through a five‐membered rhodacycle intermediate, 3‐enals were converted to C 3 ‐ or ,C 5 ‐chirogenic cyclopentanones with satisfactory yields, diastereoselectivities, and enantioselectivities. catalytic cycle theoretically calculated the origin of stereoselection is rationally explained.

Язык: Английский

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Remote Functionalization by Pd-Catalyzed Isomerization of Alkynyl Alcohols

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(27), С. 18606 - 18615

Опубликована: Июнь 28, 2024

In recent years, progress has been made in the development of catalytic methods that allow remote functionalizations based on alkene isomerization. contrast, protocols alkyne isomerization are comparatively rare. Herein, we report a general Pd-catalyzed long-range alkynyl alcohols. Starting from aryl-, heteroaryl-, or alkyl-substituted precursors, optimized system provides access preferentially to thermodynamically more stable α,β-unsaturated aldehydes and is compatible with potentially sensitive functional groups. We showed migration both π-components carbon–carbon triple bond can be sustained over several methylene units. Computational investigations served shed light key elementary steps responsible for reactivity selectivity. These include an unorthodox phosphine-assisted deprotonation rather than conventional β-hydride elimination final tautomerization event.

Язык: Английский

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