Visible‐Light‐Induced Diradical‐Mediatedipso‐Cyclization towards Double Dearomative [2+2]‐Cycloaddition or Smiles‐Type Rearrangement DOI

Guangjin Zhen,

Guohui Zeng,

Kai Jiang

et al.

Chemistry - A European Journal, Journal Year: 2022, Volume and Issue: 29(15)

Published: Dec. 3, 2022

When mono-radical ipso-cyclization of aryl sulfonamides tend to undergo Smiles-type rearrangement through aromatization-driven C-S bond cleavage, diradical-mediated cyclization must perform in a distinct reaction pathway. It is interesting meanwhile challenging tune the rate cleavage achieve chemically divergent (hetero) visible-light induced energy transfer (EnT) pathway involving diradical species. Herein based on designed indole-tethered (hetero)arylsulfonamides reported which involves and controllable an inherent bond. The combined experimental computational results have revealed that these substrates can be controlled by tuning heteroaryl moieties: a) If (hetero)aryl thienyl, furyl, phenanthryl, etc., radical coupling double dearomative diradicals (DDDR) precedes over afford cyclobutene fused indolines [2+2]-cycloaddition; b) if phenyl, naphthyl, pyridyl, indolyl DDDR favored biaryl products.

Language: Английский

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

Roman Kleinmans,

Constantin G. Daniliuc

et al.

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(44), P. 20207 - 20213

Published: Oct. 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.

Language: Английский

Citations

128

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

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(8), P. 5232 - 5241

Published: Feb. 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.

Language: Английский

Citations

43

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

Neetu Sharma,

Paige A. Royalty

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(14), P. 10142 - 10149

Published: March 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.

Language: Английский

Citations

28

The Impact of Boron Hybridisation on Photocatalytic Processes DOI Creative Commons

Alessandro Marotta,

Callum E. Adams,

John J. Molloy

et al.

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(38)

Published: June 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.

Language: Английский

Citations

56

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

39

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

Dingding Xia,

Rong-Kai Wu, Jinxin Wang

et al.

ACS Catalysis, Journal Year: 2023, Volume and Issue: 13(14), P. 9806 - 9816

Published: July 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.

Language: Английский

Citations

36

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

et al.

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(25)

Published: April 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.

Language: Английский

Citations

11

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

Somanea Tranin,

Yu‐Che Chang

et al.

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 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.

Language: Английский

Citations

2

Boronic Ester Enabled [2 + 2]-Cycloadditions by Temporary Coordination: Synthesis of Artochamin J and Piperarborenine B DOI
Yanyao Liu, Dongshun Ni, M. Kevin Brown

et al.

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(41), P. 18790 - 18796

Published: Oct. 6, 2022

A strategy for the photosensitized cycloaddition of alkenylboronates and allylic alcohols by a temporary coordination is presented. The process allows synthesis diverse range cyclobutylboronates. Key to development these reactions alcohol Bpin unit. This not only reaction proceed in an intramolecular manner but also high levels stereo regiocontrol. key aspect studies utility cycloadducts complex natural products artochamin J piperarborenine B.

Language: Английский

Citations

34

Metal–Organic Bichromophore Lowers the Upconversion Excitation Power Threshold and Promotes UV Photoreactions DOI Creative Commons
Han Li, Cui Wang, Felix Glaser

et al.

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(20), P. 11402 - 11414

Published: May 15, 2023

Sensitized triplet–triplet annihilation upconversion is a promising strategy to use visible light for chemical reactions requiring the energy input of UV photons. This avoids unsafe ultraviolet sources and can mitigate photo-damage provide access reactions, which filter effects hamper direct excitation. Here, we report new approach make blue-to-UV more amenable photochemical applications. The tethering naphthalene unit cyclometalated iridium(III) complex yields bichromophore with high triplet (2.68 eV) naphthalene-based reservoir featuring lifetime 72.1 μs, roughly factor 20 longer than photoactive excited state parent complex. In combination three different annihilators, consistently lower thresholds crossover from quadratic into linear excitation power dependence regime were observed compared system composed 2,5-diphenyloxazole annihilator sufficiently robust under long-term blue irradiation continuously high-energy singlet-excited that drive normally light. Both photoredox transfer catalyses feasible using this concept, including reductive N–O bond cleavage Weinreb amides, C–C coupling reaction based on aryl debromination, two Paternò–Büchi [2 + 2] cycloaddition reactions. Our work seems relevant in context developing strategies driving energetically demanding photochemistry low-energy

Language: Английский

Citations

21