A Heck reaction/photochemical alkene isomerization sequence to prepare functionalized quinolines

Kelly, Alex; Hoffman, Jack B.; Hoff, Oskar; Walker, Johannes C. L.; Werrel, Simon; Donohoe, Timothy J.

doi:10.1016/j.tet.2020.131396

Cited by 3 publications

(1 citation statement)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This general concept of unifying selective direct excitation with a coupling/aromatization event has most recently been applied to the synthesis of medicinally relevant quinoline scaffolds (176)(177)(178)Scheme 35). 327 In this process, a Heck reaction enables access to the E-isomer of β-phenyl enones which contain an ortho-amino group. Exposure to UV light irradiation generates a photostationary state equilibrium of isomers.…”

Section: Isomerization Enabled Cascade Synthesis: Reactivity Through ...mentioning

confidence: 99%

Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

et al. 2021

View full text Add to dashboard Cite

Geometrical E → Z alkene isomerization is intimately entwined in the historical fabric of organic photochemistry and is enjoying a renaissance (Roth et al. Angew. Chem., Int. Ed. Engl. 1989 28, 1193–1207). This is a consequence of the fundamental stereochemical importance of Z-alkenes, juxtaposed with frustrations in thermal reactivity that are rooted in microscopic reversibility. Accessing excited state reactivity paradigms allow this latter obstacle to be circumnavigated by exploiting subtle differences in the photophysical behavior of the substrate and product chromophores: this provides a molecular basis for directionality. While direct irradiation is operationally simple, photosensitization via selective energy transfer enables augmentation of the alkene repertoire to include substrates that are not directly excited by photons. Through sustained innovation, an impressive portfolio of tailored small molecule catalysts with a range of triplet energies are now widely available to facilitate contra-thermodynamic and thermo-neutral isomerization reactions to generate Z-alkene fragments. This review is intended to serve as a practical guide covering the geometric isomerization of alkenes enabled by energy transfer catalysis from 2000 to 2020, and as a logical sequel to the excellent treatment by Dugave and Demange (Chem. Rev. 2003 103, 2475–2532). The mechanistic foundations underpinning isomerization selectivity are discussed together with induction models and rationales to explain the counterintuitive directionality of these processes in which very small energy differences distinguish substrate from product. Implications for subsequent stereospecific transformations, application in total synthesis, regioselective polyene isomerization, and spatiotemporal control of pre-existing alkene configuration in a broader sense are discussed.

show abstract

Section: Isomerization Enabled Cascade Synthesis: Reactivity Through ...mentioning

confidence: 99%

Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

et al. 2021

View full text Add to dashboard Cite

show abstract

Integrating Regioselective E→Z Isomerization of Trienones with Cascade Sequences under Photosensitizer‐Free Direct Irradiation at 390 nm

Maity

Ghosh

Das

2023

Chemistry A European J

View full text Add to dashboard Cite

The regioselective E!Z isomerization of a target olefin unit embedded in a conjugated polyene is challenging. Examples are limited to retinal and its derivatives only. The problem is further amplified when such an isomerization is integrated into cascade sequences, among which the regioselectivity and subsequent directionality are the major bottlenecks. Indeed, there are no reports till date for such a transformation. Herein, it is reported that such a controlled isomerization and subsequent cyclization cascade can be enabled by photosensitizer-free direct irradiation of linearly conjugated acyclic polyenes in dichloromethane solvent using a 390 nm LED. The directionality results from deconjugation of the extended π-system in the transient Z-isomer due to stabilizing n!π* interactions between 1,4-dicarbonyls (C=O!C=O) or 1,4-carbonyl/-aryl (C=O!aryl) groups. The involvement of such noncovalent interactions has been supported by X-ray crystallography and control experiments. Thus, conjugated trienones can be stereoselectively converted into oxabicyclo[3.2.1]octadienes in an atom-and stepeconomic manner, including the first example by regioselective isomerization of a tetrasubstituted alkene. The reaction conditions are very general (> 46 examples). The reaction can be conducted under open air atmosphere at ambient temperature. Such a cascade cyclization can also be realized in solid state.

show abstract

Metal-free three-component assemblies of anilines, α-keto acids and alkyl lactates for quinoline synthesis and their anti-inflammatory activity

et al. 2022

View full text Add to dashboard Cite

show abstract

A Heck reaction/photochemical alkene isomerization sequence to prepare functionalized quinolines

Cited by 3 publications

References 53 publications

Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

Advances in theE → ZIsomerization of Alkenes Using Small Molecule Photocatalysts

Integrating Regioselective E→Z Isomerization of Trienones with Cascade Sequences under Photosensitizer‐Free Direct Irradiation at 390 nm

Metal-free three-component assemblies of anilines, α-keto acids and alkyl lactates for quinoline synthesis and their anti-inflammatory activity

Contact Info

Product

Resources

About