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

Photocatalytic Z/E isomerization unlocking the stereodivergent construction of axially chiral alkene frameworks DOI Creative Commons
Jie Wang,

Jun Gu,

Jiayu Zou

et al.

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

Published: April 16, 2024

Abstract The past century has witnessed a large number of reports on the Z / E isomerization alkenes. However, vast majority them are still limited to di- and tri-substituted stereospecific tetrasubstituted alkenes remains be an underdeveloped area, thus lacking in stereodivergent synthesis axially chiral Herein we report atroposelective alkene analogues by asymmetric allylic substitution-isomerization, followed their via triplet energy transfer photocatalysis. In this regard, N -vinylquinolinones is achieved efficiently. Mechanistic studies indicate that benzylic radical generation distribution two key factors for preserving enantioselectivities compounds.

Language: Английский

Citations

18
BrCF2CN for photocatalytic cyanodifluoromethylation DOI Creative Commons

Xinjun Yang,

Jin‐Hong Lin, Ji‐Chang Xiao

et al.

Nature Communications, Journal Year: 2025, Volume and Issue: 16(1)

Published: Jan. 7, 2025

Considering the unique electronic properties of CF2 and CN groups, CF2CN group has significant potential in drug agrochemical development, as well material sciences. However, incorporating a remains considerable challenge. In this work, we disclose use bromodifluoroacetonitrile (BrCF2CN), cost-effective readily available reagent, radical source for cyanodifluoromethylation alkyl alkenes, aryl alkynes, (hetero)arenes under photocatalytic conditions. This protocol demonstrates an exceptionally broad substrate scope remarkable tolerance to various functional groups. Notably, alkynes predominantly provides sterically hindered thermodynamically unfavorable outcome, (hetero)arene C-H bonds are directly amenable without pre-functionalization. Here, authors report (BrCF2CN)

Language: Английский

Citations

3
One-Metal/Two-Ligand for Dual Activation Tandem Catalysis: Photoinduced Cu-Catalyzed Anti-hydroboration of Alkynes DOI Creative Commons
Javier Corpas, Miguel Gomez‐Mendoza, Jonathan Ramírez-Cárdenas

et al.

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(28), P. 13006 - 13017

Published: July 5, 2022

A dual catalyst system based on ligand exchange of two diphosphine ligands possessing different properties in a copper complex has been devised to merge metal- and photocatalytic activation modes. This strategy applied the formal anti-hydroboration activated internal alkynes via tandem sequence which Cu/Xantphos catalyzes B2pin2-syn-hydroboration alkyne whereas Cu/BINAP serves as photocatalyst for visible light-mediated isomerization resulting alkenyl boronic ester. Photochemical studies by means UV–vis absorption, steady-state time-resolved fluorescence, transient absorption spectroscopy have allowed characterizing photoactive species reaction its interaction with intermediate syn-alkenyl ester through energy transfer from triplet excited state catalyst. In addition, mechanistic shed light into speciation interplay between catalytic cycles critical success factors.

Language: Английский

Citations

39
Direct Observation of Triplet States in the Isomerization of Alkenylboronates by Energy Transfer Catalysis DOI
Till J. B. Zähringer,

Max Wienhold,

Ryan Gilmour

et al.

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(39), P. 21576 - 21586

Published: Sept. 20, 2023

Alkenylboronates are versatile building blocks for stereocontrolled synthesis owing to the traceless nature of boron group that can be leveraged achieve highly selective geometric isomerization. Using thioxanthone as an inexpensive photocatalyst, photoisomerization these species continues provide expansive platform stereodivergent synthesis, particularly in construction bioactive polyenes. Although mechanistic investigations consistent with light-driven energy transfer, direct experimental evidence remains conspicuously absent. Herein, we report a rigorous investigation using two widely used alkenylboronates alongside relevant reference compounds. Through combination irradiation experiments, transient absorption spectroscopic studies, kinetic modeling, and DFT calculations all isomers model compounds, it has been possible unequivocally detect characterize perpendicular triplet generated by transfer. Our results serve not only blueprint studies challenging organic sensitizers, but guidelines delineated have also enabled development more sustainable reaction conditions: first time, efficient organocatalytic isomerization under sunlight become feasible.

Language: Английский

Citations

35
Stereoselective Synthesis of Trisubstituted Alkenes via Copper Hydride-Catalyzed Alkyne Hydroalkylation DOI
Dennis A. Kutateladze, Binh Khanh, Yuyang Dong

et al.

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(32), P. 17557 - 17563

Published: Aug. 4, 2023

Alkenes are ubiquitous in organic chemistry, yet many classes of alkenes remain challenging to access by current synthetic methodology. Herein, we report a copper hydride-catalyzed approach for the synthesis Z-configured trisubstituted with high stereo- and regioselectivity via alkyne hydroalkylation. A DTBM-dppf-supported Cu catalyst was found be optimal, providing substantial increase product yield compared reactions conducted dppf as ligand. DFT calculations show that DTBM substitution leads acceleration hydrocupration through combined ground transition state effects related preventing dimerization enhancing catalyst–substrate dispersion interactions, respectively. Alkyne hydroalkylation successfully demonstrated methyl larger alkyl tosylate electrophiles produce variety (hetero)aryl-substituted moderate yields complete selectivity Z stereochemically configured products. In formation key C–C bond, computational studies revealed direct SN2 pathway alkylation vinylcopper intermediate situ-formed iodides.

Language: Английский

Citations

22
Palladium‐Catalyzed Alkyne Hydrocyanation toward Ligand‐Controlled Stereodivergent Synthesis of (E)‐ and (Z)‐Trisubstituted Acrylonitriles DOI

Jinguo Long,

Ruihua Zhao,

Gui‐Juan Cheng

et al.

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(26)

Published: April 27, 2023

We herein describe a palladium-catalyzed hydrocyanation of propiolamides for the stereodivergent synthesis trisubstituted acrylonitriles. This synthetic method tolerated various primary, secondary and tertiary propiolamides. The cautious selection suitable ligand is essential to success this process. Control experiments indicate intermediacy E-acrylonitriles, which lead Z-acrylonitriles via isomerization. density functional theory calculations suggests that bidentate L2 enables feasible cyclometallation/isomerization pathway E Z isomerization, while monodentate L1 inhibits leading divergent stereoselectivity. usefulness can be demonstrated by readily derivatization products give E- Z-trisubstituted alkenes. In addition, Z-acrylonitrile have also been successfully employed in cycloaddition reactions.

Language: Английский

Citations

17
Regio- and Stereoselective Electrochemical Alkylation of Morita–Baylis–Hillman Adducts DOI Creative Commons
Giulio Bertuzzi,

Giada Ombrosi,

Marco Bandini

et al.

Organic Letters, Journal Year: 2022, Volume and Issue: 24(24), P. 4354 - 4359

Published: June 14, 2022

Electrosynthesis is effectively employed in a general regio- and stereoselective alkylation of Morita–Baylis–Hillman compounds. The exposition N-acyloxyphthalimides (redox-active esters) to galvanostatic electroreductive conditions, following the sacrificial-anode strategy, proved an efficient practical method access densely functionalized cinnamate oxindole derivatives. High yields (up 80%) wide functional group tolerance characterized methodology. A tentative mechanistic sketch proposed based on dedicated control experiments.

Language: Английский

Citations

23
Kinetic Resolution of 2-Cinnamylpyrrolines Enabled by Photoexcited Chiral Copper Complex-Mediated Alkene E → Z Isomerization DOI
Hao Zhang,

Xian He,

Xiang‐Ai Yuan

et al.

ACS Catalysis, Journal Year: 2023, Volume and Issue: 13(5), P. 2857 - 2866

Published: Feb. 10, 2023

The two-dimensional (2D) stereochemical information transformed into three-dimensional (3D) chemical space through stereospecific reactions is expansive in the discovery of biologically or pharmacologically active molecules. Alkene subunits are ubiquitous structural motifs and constitute diverse inexpensive start points for this endeavor. Herein, a kinetic resolution enabled by photoexcited chiral copper complex-mediated alkene E → Z isomerization disclosed, leading to enantiodivergent synthesis 2-cinnamylpyrrolines. Mechanistic experiments density functional theory (DFT) calculations gave reasons observed efficiency, which cooperative result different association abilities between two enantiomers complex (ground-state thermodynamics) overall sensitization rates substrate–catalyst (excited-state kinetics). This revitalized protocol has shown wide group compatibility explore 3D space, brings another level advance complementarity ingenious control stereochemistry triplet-state photoreactions.

Language: Английский

Citations

14
Divergent 1,2-carboallylation of terminal alkynes enabled by metallaphotoredox catalysis with switchable triplet energy transfer DOI Creative Commons
Jian Qin,

Zhuzhu Zhang,

Yi Lu

et al.

Chemical Science, Journal Year: 2023, Volume and Issue: 14(43), P. 12143 - 12151

Published: Jan. 1, 2023

We report a selective and stereodivergent three-component carboallylation of terminal alkynes with allylic carbonates alkyl trifluoroborates via metallaphotoredox catalysis pyrene as triplet energy transfer (EnT) modulator.

Language: Английский

Citations

12
Catalyst-Enabled Stereodivergence in Photochemical Atom Transfer Radical Addition (ATRA) of α-Iodoboronic Esters to Alkynes DOI

Qi Fan,

Jiawu Huang,

Shuang Lin

et al.

ACS Catalysis, Journal Year: 2023, Volume and Issue: 14(1), P. 299 - 307

Published: Dec. 16, 2023

The atom transfer radical addition (ATRA) to alkynes is a valuable strategy for the synthesis of allylic substituted molecules, yet it has not been applied boronic acids or their esters, which are important building blocks in organic synthesis. inherent challenge ATRA reactions control geometric selectivity. By employing different alkene isomerization techniques, namely, photochemical uphill catalysis and manganese-catalyzed halogen-abstraction/radical rebound processes, we able synthesize both isomers iodinated esters stereoselective manner. Mechanistic investigations reveal dual functionalities catalysts, acting as catalysts processes. protocols feature broad substrate scope good functional group tolerance. Importantly, iodo boryl moieties within products provide orthogonal handles further synthetic manipulations. employed here should inspire more efforts toward alkynes.

Language: Английский

Citations

11