[2 + 2] Photocycloadditions of Conformationally Constrained Styrenes Enabled by Triplet Lifetime Extension DOI

Christina Cong,

Nicholas J. Fastuca, Alberto Castanedo

и другие.

The Journal of Organic Chemistry, Год журнала: 2025, Номер unknown

Опубликована: Июнь 3, 2025

We report an intermolecular, cross-selective [2 + 2] cycloaddition between cyclic styrenes and olefin acceptors proceeding via visible-light irradiation, enabled by the extended triplet lifetime of styrenes. A broad range olefins, including electron-deficient simple alkenes, (hetero)styrenes, arylimines, vinyl boronate esters, among others, underwent efficient with constrained four-, five-, rigidified six-membered rings, providing rapid access to sp3-rich fused cyclobutane scaffolds. Notably, two electronically similar styrenes, which typically gives statistical mixtures homo- heterodimers, proceeded excellent chemoselectivity yield acyclic without requiring a large excess one reactant, facilitated significant difference in reacting partners. Mechanistic studies DFT calculations support Dexter energy transfer mechanism substrate activation underscore critical role extension enabling observed reactivity. The utility this method is demonstrated total synthesis lindleyanin, only steps.

Язык: Английский

Synthesis of Polysubstituted 2-Oxabicyclo[2.1.1]hexanes via Visible-Light-Induced Energy Transfer DOI
Yujie Liang,

Roman Kleinmans,

Constantin G. Daniliuc

и другие.

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(44), С. 20207 - 20213

Опубликована: Окт. 27, 2022

Synthesis of bicyclic scaffolds has attracted growing interest because they are high importance in modern pharmaceutical development. Here we report a strategy to access polysubstituted 2-oxabicyclo[2.1.1]hexanes single operation from readily accessible benzoylformate esters and bicyclo[1.1.0]butanes via visible-light-induced triplet energy transfer catalysis. The process is proposed involve formal [2π + 2σ] photocycloaddition/backbone C-H abstraction/aryl group migration sequence. A diverse range (hetero)aryl groups successfully underwent the backbone (C2) position provide previously inaccessible molecules, ester product can serve as handle for downstream manipulation, thus offering opportunities rapidly build up molecular complexity new sp3-rich chemical space.

Язык: Английский

Процитировано

128
Double Strain-Release [2π+2σ]-Photocycloaddition DOI
Subhabrata Dutta, Yilin Lu, Johannes E. Erchinger

и другие.

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(8), С. 5232 - 5241

Опубликована: Фев. 13, 2024

In pursuit of potent pharmaceutical candidates and to further improve their chemical traits, small ring systems can serve as a potential starting point. Small units have the additional merit loaded strain at core, making them suitable reactants they capitalize on this intrinsic driving force. With introduction cyclobutenone strained precursor ketene, photocycloaddition with another unit, bicyclo[1.1.0]butane (BCB), enables reactivity both π-units in transient ketene. This double strain-release driven [2π+2σ]-photocycloaddition promotes synthesis diverse heterobicyclo[2.1.1]hexane units, pharmaceutically relevant bioisostere. The effective under catalyst-free conditions high functional group tolerance defines its synthetic utility. Experimental mechanistic studies density theory (DFT) calculations suggest that takes place via triplet mechanism.

Язык: Английский

Процитировано

42
Synthesis of Borylated Carbocycles by [2 + 2]-Cycloadditions and Photo-Ene Reactions DOI
Jarett M. Posz,

Neetu Sharma,

Paige A. Royalty

и другие.

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(14), С. 10142 - 10149

Опубликована: Март 27, 2024

Saturated bicyclic compounds make up a valuable class of building blocks in the development agrochemicals and pharmaceuticals. Here, we present synthesis borylated bicyclo[2.1.1]hexanes via crossed [2 + 2]-cycloaddition. Due to presence C–B bond, variety structures can be easily prepared that are not accessible by other methods. Moreover, rare photo-ene reaction is also disclosed, allowing for diastereoselective trisubstituted cyclopentanes.

Язык: Английский

Процитировано

28
The Impact of Boron Hybridisation on Photocatalytic Processes DOI Creative Commons

Alessandro Marotta,

Callum E. Adams,

John J. Molloy

и другие.

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(38)

Опубликована: Июнь 24, 2022

Recently the fruitful merger of organoboron chemistry and photocatalysis has come to forefront organic synthesis, resulting in development new technologies access complex (non)borylated frameworks. Central success this combination is control boron hybridisation. Contingent on photoactivation mode, as its neutral planar form or tetrahedral boronate can be used regulate reactivity. This Minireview highlights current state art photocatalytic processes utilising compounds, paying particular attention role hybridisation for target transformation.

Язык: Английский

Процитировано

56
Direct Observation of Triplet States in the Isomerization of Alkenylboronates by Energy Transfer Catalysis DOI
Till J. B. Zähringer,

Max Wienhold,

Ryan Gilmour

и другие.

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(39), С. 21576 - 21586

Опубликована: Сен. 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.

Язык: Английский

Процитировано

39
Visible-Light-Mediated Energy Transfer Enables Cyclopropanes Bearing Contiguous All-Carbon Quaternary Centers DOI

Dingding Xia,

Rong-Kai Wu, Jinxin Wang

и другие.

ACS Catalysis, Год журнала: 2023, Номер 13(14), С. 9806 - 9816

Опубликована: Июль 11, 2023

Cyclopropanes bearing contiguous all-carbon quaternary centers continue to attract attention due their bioactivities. However, methods obtain cyclopropanes with remain largely unexplored the high steric hindrance of these compounds. Herein, we report a visible-light-mediated energy-transfer (EnT) strategy realize in situ donor/donor carbenes from readily available N-tosylhydrazones, facilitating synthesis highly congested EWG-free cyclopropanes. Through this approach, are rapidly installed into complex bioactive molecules, fluorescent and other useful building blocks that challenging synthesize. Detailed mechanistic reactions DFT studies clearly demonstrated role photosensitizer, formation carbenes, necessity light base system.

Язык: Английский

Процитировано

35
PolyBorylated Alkenes as Energy‐Transfer Reactive Groups: Access to Multi‐Borylated Cyclobutanes Combined with Hydrogen Atom Transfer Event DOI Creative Commons
Nicole Hanania, Nadim Eghbarieh, Ahmad Masarwa

и другие.

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(25)

Опубликована: Апрель 11, 2024

Abstract While polyborylated alkenes are being recognized for their elevated status as highly valuable reagents in modern organic synthesis, allowing efficient access to a diverse array of transformations, including the formation C−C and C‐heteroatom bonds, potential energy‐transfer reactive groups has remained unexplored. Yet, this holds key generating elusive biradical species, which can be captured by olefins, thereby leading construction new highly‐borylated scaffolds. Herein, we report designed strategy photosensitized [2+2]‐cycloadditions poly‐borylated with various olefins enabling regioselective synthesis cyclobutane motifs, 1,1‐di‐, 1,1,2‐tri‐, 1,1,2,2‐tetra‐borylated cyclobutanes. In fact, these compounds belong family that presently lacks synthetic pathways. Interestingly, when α‐methylstyrene was used, reaction involves an interesting 1,5‐hydrogen atom transfer (HAT). Mechanistic deuterium‐labeling studies have provided insight into outcome process. addition, cyclobutanes then demonstrated useful selective oxidation processes resulting cyclobutanones γ‐lactones.

Язык: Английский

Процитировано

11
Facile Synthesis of Housanes by an Unexpected Strategy DOI
Yanyao Liu,

Somanea Tranin,

Yu‐Che Chang

и другие.

Journal of the American Chemical Society, Год журнала: 2025, Номер unknown

Опубликована: Фев. 17, 2025

Rigid bicyclic hydrocarbons have emerged as important building blocks in the drug discovery industry. Despite progress this general area, bicyclo[2.1.0]pentanes (housanes) are an understudied class of molecules. Herein we report unconventional synthesis borylated housanes. Our method features a broad scope and high diastereoselectivities versatile intermediates. The route involves strain-release diboration bicyclo[1.1.0]butane intramolecular deborylative alkylation. versatility bridgehead boronic ester was demonstrated several functionalizations. Lastly, mechanism reaction investigated, unusual stereospecific diastereoselective ring expansion uncovered.

Язык: Английский

Процитировано

2
Synthesis of (+)-Saxitoxin Facilitated by a Chiral Auxiliary for Photocycloadditions Involving Alkenylboronate Esters DOI

Jiao Yang,

Jiaqi Liu, Wuxiang Mao

и другие.

Journal of the American Chemical Society, Год журнала: 2025, Номер unknown

Опубликована: Март 10, 2025

(+)-Saxitoxin, a potent neurotoxin and NaV blocker, poses significant synthetic challenges due to its compact tricyclic framework guanidinium moieties. We report concise asymmetric total synthesis featuring an intramolecular [2 + 2] photocycloaddition of alkenylboronate ester equipped with new chiral auxiliary. This auxiliary, compatible UV light easily exchangeable on B(pin) derivatives, enabled high stereocontrol through hydrogen-bond-mediated transition-state stabilization. Our approach not only introduces innovative surrogate for Michael addition, particularly addressing transformations contra-thermodynamic barriers, but also highlights the potential boron-enabled photochemistry synthesizing complex molecules.

Язык: Английский

Процитировано

1
Synthesis of Fused-Housane Derivatives via Intramolecular [2 + 2] Photocycloaddition DOI

David Suárez‐García,

Miguel A. Rodrı́guez, Iratxe Barbolla

и другие.

Organic Letters, Год журнала: 2025, Номер unknown

Опубликована: Апрель 9, 2025

Herein, we describe a [2 + 2] photocycloaddition of cyclopropenes bearing styryl group to prepare housane derivatives. The reaction occurs via selective excitation the styrene fragment, enabling completely stereoselective stepwise cycloaddition. Fused-housane derivatives with an unprecedented substitution pattern are prepared in simple manner using convenient visible light.

Язык: Английский

Процитировано

1