Visible Light Promoted Functionalisation of Carbon-Carbon Sigma Bonds

The use of visible light to activate transition metal catalysts towards redox processes has transformed the way organic molecules can be constructed. Promotion of an electron to an excited state enables the generation of organic radicals through electron transfer to or from the metal complex, with the resulting radicals primed for reactions such as addition to carbon–carbon pi bonds. Despite advances in photoredox catalysis which have led to the discovery of numerous such methods for bond construction, this mild approach to the generation of free radicals has not been applied to the functionalisation of carbon–carbon sigmabonds. Here we report the first such use of photoredox catalysis to promote the addition of organic halides to the caged carbocycle [1.1.1]propellane; the products of this process are bicyclo[1.1.1]pentanes (BCPs), motifs that are of high importance as bioisosteres in the pharmaceutical industry, and in materials applications. The methodology shows broad substrate scope and functional group tolerance, and is applicable to both sp2and sp3carbon–halogen bonds, while the use of substrates containing alkene acceptors enables the single-step construction of polycyclic bicyclopentane products through cyclisation cascades. Finally, the potential to accelerate drug discovery is demonstrated through examples of late-stage bicyclopentylation to access natural product- and drug-like molecules.

Download Full-text

Visible-light-induced three-component 1,2-difluoroalkylarylation of styrenes with α-carbonyl difluoroalkyl bromides and indoles

Organic Chemistry Frontiers ◽

10.1039/c6qo00393a ◽

2016 ◽

Vol 3 (11) ◽

pp. 1443-1446 ◽

Cited By ~ 30

Author(s):

Yingqian Duan ◽

Weipeng Li ◽

Pan Xu ◽

Muliang Zhang ◽

Yixiang Cheng ◽

...

Keyword(s):

Visible Light ◽

Single Step ◽

Photoredox Catalysis

A novel visible light photoredox catalysis three-component 1,2-difluoroalkylarylation of styrenes was disclosed, and two new C–C bonds were generated in a single step through regioselective incorporation of a CF2 group and a variety of indoles to CC bonds.

Download Full-text

Bromine Cation Initiated vic-Diphosphination of Styrenes with Diphosphines under Photoredox Catalysis

Synthesis ◽

10.1055/s-0037-1609447 ◽

2018 ◽

Vol 50 (17) ◽

pp. 3402-3407 ◽

Cited By ~ 9

Author(s):

Koji Hirano ◽

Masahiro Miura ◽

Nobutaka Otomura ◽

Yuto Okugawa

Keyword(s):

Visible Light ◽

Functional Group ◽

Single Electron ◽

Photoredox Catalysis ◽

Reaction Efficiency ◽

Key Species ◽

Electron Reduction

An N-bromosuccinimide (NBS)-initiated vic-diphosphination of styrenes with diphosphines proceeds under visible-light-promoted Ir(ppy)3 photoredox catalysis to deliver the corresponding 1,2-diphosphinoethane derivatives in good yields. The NBS is a bromine cation source and generates a bromophosphine, which undergoes a single-electron reduction by the excited iridium species to form phosphinyl radicals of key species in the diphoshination reaction. The newly developed photoredox catalysis demonstrates better reaction efficiency, functional group compatibility, and scalability than the previous photocatalysis using N-fluorobenzenesulfonimide (NFSI) and silylphosphine.

Download Full-text

Photoredox catalysis by [Ru(bpy)3]2+ to trigger transformations of organic molecules. Organic synthesis using visible-light photocatalysis and its 20th century roots

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc2011078 ◽

2011 ◽

Vol 76 (7) ◽

pp. 859-917 ◽

Cited By ~ 411

Author(s):

Filip Teplý

Keyword(s):

Visible Light ◽

Organic Synthesis ◽

Organic Molecules ◽

Recent Literature ◽

Synthetic Methods ◽

Bond Breaking ◽

Materials Chemistry ◽

Photoredox Catalysis ◽

Contemporary Work ◽

Developing Area

Reactions triggered by light constitute a treasure trove of unique synthetic methods that are available to chemists. Photoinduced redox processes using visible light in conjunction with sensitizing dyes offer a great variety of catalytic transformations useful in the realm of organic synthesis. The recent literature amply shows that this preparative toolbox is expanding substantially. This review discusses historical and contemporary work in the area of photoredox catalysis with [Ru(bpy)3]2+. Elegant examples from the most recent literature document the importance of this fast developing area of research. The photoredox chemistry has also emerged as a promising bond-making and bond-breaking tool for chemical biology and materials chemistry. A review with 96 references.

Download Full-text

Benzylic C−H acylation by cooperative NHC and photoredox catalysis

Nature Communications ◽

10.1038/s41467-021-22292-z ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Qing-Yuan Meng ◽

Lena Lezius ◽

Armido Studer

Keyword(s):

Organic Molecules ◽

Functional Group ◽

Photoredox Catalysis ◽

Diverse Range ◽

Site Selectivity ◽

Aryl Ketones ◽

Direct Acylation ◽

Selective Acylation ◽

Site Selective ◽

Complex Organic

AbstractMethods that enable site selective acylation of sp3 C-H bonds in complex organic molecules are not well explored, particularly if compared with analogous transformations of aromatic and vinylic sp2 C-H bonds. We report herein a direct acylation of benzylic C-H bonds by merging N-heterocyclic carbene (NHC) and photoredox catalysis. The method allows the preparation of a diverse range of benzylic ketones with good functional group tolerance under mild conditions. The reaction can be used to install acyl groups on highly functionalized natural product derived compounds and the C-H functionalization works with excellent site selectivity. The combination of NHC and photoredox catalysis offers options in preparing benzyl aryl ketones.

Download Full-text

Recent Advances in Visible-Light-Mediated Amide Synthesis

Molecules ◽

10.3390/molecules27020517 ◽

2022 ◽

Vol 27 (2) ◽

pp. 517

Author(s):

Bin Lu ◽

Wen-Jing Xiao ◽

Jia-Rong Chen

Keyword(s):

Visible Light ◽

Organic Molecules ◽

Structural Motif ◽

Radical Reactions ◽

Photoredox Catalysis ◽

Mild Conditions ◽

Amide Synthesis ◽

Functionalized Materials ◽

Activating Agent ◽

Ubiquitous Presence

Visible-light photoredox catalysis has attracted tremendous interest within the synthetic community. As such, the activation mode potentially provides a more sustainable and efficient platform for the activation of organic molecules, enabling the invention of many controlled radical-involved reactions under mild conditions. In this context, amide synthesis via the strategy of photoredox catalysis has received growing interest due to the ubiquitous presence of this structural motif in numerous natural products, pharmaceuticals and functionalized materials. Employing this strategy, a wide variety of amides can be prepared effectively from halides, arenes and even alkanes under irradiation of visible light. These methods provide a robust alternative to well-established strategies for amide synthesis that involve condensation between a carboxylic acid and amine mediated by a stoichiometric activating agent. In this review, the representative progresses made on the synthesis of amides through visible light-mediated radical reactions are summarized.

Download Full-text

Generation of Phosphoranyl Radicals via Photoredox Catalysis Enables Voltage–Independent Activation of Strong C–O Bonds

10.26434/chemrxiv.6349253 ◽

2018 ◽

Author(s):

Erin Stache ◽

Alyssa B. Ertel ◽

Tomislav Rovis ◽

Abigail G. Doyle

Keyword(s):

Carboxylic Acids ◽

Functional Groups ◽

Single Step ◽

Direct Access ◽

Photoredox Catalysis ◽

Acyl Radical ◽

Synthetic Strategy ◽

Acyl Radicals ◽

Benzyl Radicals ◽

Aliphatic Carboxylic Acids

Alcohols and carboxylic acids are ubiquitous functional groups found in organic molecules that could serve as radical precursors, but C–O bonds remain difficult to activate. We report a synthetic strategy for direct access to both alkyl and acyl radicals from these ubiquitous functional groups via photoredox catalysis. This method exploits the unique reactivity of phosphoranyl radicals, generated from a polar/SET crossover between a phosphine radical cation and an oxygen centered nucleophile. We first show the desired reactivity in the reduction of benzylic alcohols to the corresponding benzyl radicals with terminal H-atom trapping to afford the deoxygenated product. Using the same method, we demonstrate access to synthetically versatile acyl radicals which enables the reduction of aromatic and aliphatic carboxylic acids to the corresponding aldehydes with exceptional chemoselectivity. This protocol also transforms carboxylic acids to heterocycles and cyclic ketones via intramolecular acyl radical cyclizations to forge new C–O, C–N and C–C bonds in a single step.

Download Full-text

Regioselective C3-H Trifluoromethylation of 2H-Indazole Under Transition-Metal-Free Photoredox Catalysis

10.26434/chemrxiv.7796603.v1 ◽

2019 ◽

Cited By ~ 1

Author(s):

Arumugavel Murugan ◽

Venkata Nagarjuna Babu ◽

Nagaraj Sabarinathan ◽

Sharada Duddu. S

Keyword(s):

Transition Metal ◽

Visible Light ◽

Practical Approach ◽

Hypervalent Iodine ◽

Radical Mechanism ◽

Photoredox Catalysis ◽

Metal Free

Here we report a visible-light-promoted metal-free regioselective C3-H trifluoromehtylation reaction that proceeds via radical mechanism and which supported by control experiments. The combination of photoredox catalysis and hypervalent iodine reagent provides a practical approach for the present trifluoromethylation reaction and synthesis of a library of trifluoromethylated indazoles.

Download Full-text

Faculty Opinions recommendation of Batch to flow deoxygenation using visible light photoredox catalysis.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.718012691.793477212 ◽

2013 ◽

Author(s):

Steven L Castle

Keyword(s):

Visible Light ◽

Photoredox Catalysis

Download Full-text

Rhodamines as Photocatalyst in Organic Synthesis

Current Green Chemistry ◽

10.2174/2213346107999201026201232 ◽

2020 ◽

Vol 07 ◽

Author(s):

Avik K. Bagdi ◽

Papiya Sikdar

Keyword(s):

Visible Light ◽

Organic Synthesis ◽

Organic Dyes ◽

Transition Metal Catalysts ◽

Visible Light Photocatalysis ◽

Eosin Y ◽

Organic Transformations ◽

The Sustainable Development ◽

Mechanistic Pathway ◽

Green Model

Abstract:: Organic synthesis under environment friendly conditions has great impact in the sustainable development. In this context, visible light photocatalysis has emerged as a green model as this offers an energy-efficient pathway towards the organic transformation. Different transition-metal catalysts (Ir-, Ru-, Cu- etc) and organic dyes (eosin Y, rose bengal, methylene blue etc) are well-known photocatalysts in organic synthesis. Apart from the well-known organophotoredox catalysts, rhodamines (Rhodamine B and Rhodamine 6G) have been also employed as efficient photocatalysts for different organic transformations. In this review, we will focus on the photocatalysis by rhodamines in organic synthesis. Mechanistic pathway of the methodologies will also be discussed. We believe this review will stimulate the employment of rhodamines in the visible light photocatalysis for efficient organic transformations in the future.

Download Full-text