Thermally Activated Geometrical Regioselective E→Z Isomerization‐Enabled Cascade Sequences of Conjugated Dienals: Experimental and DFT Studies DOI
Jayanta Saha, Soumadip Banerjee,

Sidhartha Malo

et al.

Chemistry - A European Journal, Journal Year: 2023, Volume and Issue: 29(63)

Published: Aug. 9, 2023

The geometrical regioselective E→Z isomerization of a conjugated alkene under thermal activation pose challenge due to microscopic reversibility. Herein we report that such reversibility issues can be circumvented by integrating with subsequent cyclization cascade, particularly in the absence commonly employed light, acids, or metal-catalysts. Thus, linearly dienals mixture toluene-alcohol (2 : 1) solvents only alcohol at 60-70 °C converted γ-alkoxybutenolides moderate good yields. intermediary 2Z,4E-isomer isolated, which includes first example isolating product conditions. Density functional theory (DFT) studies have been shed light on feasibility and ensuing cascade sequences. It has observed 2E,4E→2Z,4E dienal is thermodynamically facile (ΔG <0) process. Structural elucidation further reveals presence certain charge transfer non-covalent interaction may primary reasons for enhanced stability 2Z,4E-isomer. thermodynamic plausibility reaction from Z-isomer anticipated polar protic solvent (here MeOH) also explicated. Out two probable pathways, "hemiacetal pathway" involving relay proton kinetically more feasible diminished barrier than "conjugate addition pathway".

Language: Английский

Visible-Light-Promoted 6π Photocyclization of ortho-Biaryl-Appended β-Ketoesters DOI

S. K. Zhang,

Shanshan Zhang, Junli Li

et al.

The Journal of Organic Chemistry, Journal Year: 2023, Volume and Issue: 88(13), P. 9094 - 9104

Published: June 14, 2023

A photocatalyst- and additive-free visible-light-induced 6π-photocyclization of ortho-biaryl-appended β-ketoesters has been developed. Upon irradiation with visible light, substrates undergo 6-endo-trig cyclization/1,5-H shift to 9,10-dihydrophenanthren-9-ols high efficiency selectivity. The reaction proceeds via conrotatory ring closure followed by a suprafacial 1,5-hydrogen leading the observed single trans-fused products. Preliminary mechanistic studies reveal feasibility both 1,5-H intersystem crossing diradical intermediate.

Language: Английский

Citations

7
Photocatalyst‐free, Visible Light‐mediated Paternò‐Büchi Reaction Between Dicarbonyl Compounds and Olefines DOI
Dan Zhang, Wu Chunying,

Huihui Zhou

et al.

Asian Journal of Organic Chemistry, Journal Year: 2022, Volume and Issue: 11(11)

Published: Sept. 26, 2022

Abstract The communication describes a general Paternò‐Büchi reaction under mild conditions, which is featured with visible light‐mediation, catalyst‐free and broad range of substrates comparing other strategies. Having overcome the synthetic limitations PB faces, this practical protocol can be employed to prepare variety multisubstituted oxetanes that often appear serving as important scaffolds in natural products drugs. common white light, sole driving force case, directly excite carbonyl compounds reach its triplet state, then attacks an alkenes generate diradical intermediate, resulting high diastereoselectivity.

Language: Английский

Citations

12
CO2-promoted photocatalytic aryl migration from nitrogen to carbon for switchable transformation of N-arylpropiolamides DOI Creative Commons
Ge Liu,

Denghui Ma,

Jianchen Zhang

et al.

Nature Communications, Journal Year: 2024, Volume and Issue: 15(1)

Published: Nov. 22, 2024

Language: Английский

Citations

2
Merging Grubbs second-generation catalyst with photocatalysis enablesZ-selective metathesis of olefins: scope, limitations, and mechanism DOI Creative Commons

Saïf Eddine Chérif,

Avisek Ghosh,

Saloua Chelli

et al.

Chemical Science, Journal Year: 2022, Volume and Issue: 13(41), P. 12065 - 12070

Published: Jan. 1, 2022

Light is magic! The combination of Grubbs second generation catalyst, a well-known catalyst for E -selective olefin metathesis, with photosensitizer enables efficient access to the contra-thermodynamic Z -isomers.

Language: Английский

Citations

11
Thermally Activated Geometrical Regioselective E→Z Isomerization‐Enabled Cascade Sequences of Conjugated Dienals: Experimental and DFT Studies DOI
Jayanta Saha, Soumadip Banerjee,

Sidhartha Malo

et al.

Chemistry - A European Journal, Journal Year: 2023, Volume and Issue: 29(63)

Published: Aug. 9, 2023

The geometrical regioselective E→Z isomerization of a conjugated alkene under thermal activation pose challenge due to microscopic reversibility. Herein we report that such reversibility issues can be circumvented by integrating with subsequent cyclization cascade, particularly in the absence commonly employed light, acids, or metal-catalysts. Thus, linearly dienals mixture toluene-alcohol (2 : 1) solvents only alcohol at 60-70 °C converted γ-alkoxybutenolides moderate good yields. intermediary 2Z,4E-isomer isolated, which includes first example isolating product conditions. Density functional theory (DFT) studies have been shed light on feasibility and ensuing cascade sequences. It has observed 2E,4E→2Z,4E dienal is thermodynamically facile (ΔG <0) process. Structural elucidation further reveals presence certain charge transfer non-covalent interaction may primary reasons for enhanced stability 2Z,4E-isomer. thermodynamic plausibility reaction from Z-isomer anticipated polar protic solvent (here MeOH) also explicated. Out two probable pathways, "hemiacetal pathway" involving relay proton kinetically more feasible diminished barrier than "conjugate addition pathway".

Language: Английский

Citations

6