Asian Journal of Organic Chemistry

Cover image for Vol. 6 Issue 2

Managing Editor: Theresa Kueckmann; Editorial Board Chairs: Sung Ho Kang, Keiji Maruoka, Jian Pei

Impact Factor: 3.275

ISI Journal Citation Reports © Ranking: 2015: 16/59 (Chemistry Organic)

Online ISSN: 2193-5815

Associated Title(s): Advanced Synthesis & Catalysis, Chemistry – An Asian Journal, ChemNanoMat, European Journal of Organic Chemistry

Virtual Issue

Photoredox Catalysis

Photoredox catalysis is currently one of the hottest research areas in organic chemistry. The number of publications has increased by a factor of 10 in less than five years, culminating in more than 500 articles in 2016. In photoredox catalysis, the catalyst is excited by visible light and, while in the excited state, induces single electron transfer (SET) processes in the substrates and thus facilitates reactions that might otherwise not occur. Afterwards, the photocatalyst relaxes back to the ground state, ready for a new light-induced catalytic cycle.

This virtual issue combines papers published in special issues of Eur. J. Org. Chem. and Asian J. Org. Chem. (issue editor: Burkhard König, University Regensburg), showcasing the state of the art in the field.

Quantitative Profiling of the Heavy-Atom Effect in BODIPY Dyes: Correlating Initial Rates, Atomic Numbers, and 1O2 Quantum Yields

Quantitative Profiling of the Heavy-Atom Effect in BODIPY Dyes: Correlating Initial Rates, Atomic Numbers, and 1O2 Quantum Yields

Yannick P. Rey, Dario G. Abradelo, Nico Santschi, Cristian A. Strassert*, Ryan Gilmour*

A GC-based method to assess catalyst performance is developed and validated with a set of halogenated BODIPY scaffolds. An initial-rate approximation is applied to a model transformation, and the trend follows the heavy-atom effect (v0,H < v0,Cl < v0,Br < v0,I). This approach is corroborated by determinations of absolute 1O2 and photoluminescent quantum yields and time-resolved luminescence decays.

Eur. J. Org. Chem. 10.1002/ejoc.201601372 [Full Paper]

Proton-Coupled Electron Transfer in Photoredox Catalytic Reactions

Proton-Coupled Electron Transfer in Photoredox Catalytic Reactions

Norbert Hoffmann*

Proton-coupled electron transfer facilitates partial steps in photoredox catalytic reactions when corresponding electron transfer is endergonic. The scope of such reactions is considerably enlarged by such processes.

Eur. J. Org. Chem. 10.1002/ejoc.201601445 [Microreview]

Decarboxylative Giese-Type Reaction of Carboxylic Acids Promoted by Visible Light: A Sustainable and Photoredox-Neutral Protocol

Decarboxylative Giese-Type Reaction of Carboxylic Acids Promoted by Visible Light: A Sustainable and Photoredox-Neutral Protocol

Nieves P. Ramirez, Jose C. Gonzalez-Gomez*

The decarboxylative alkylation of carboxylic acids can be efficiently promoted by visible light under air at room temperature by using 9-mesitylene-10-methylacridinium perchlorate ([Acr-Mes]ClO4) as photocatalyst. A range of readily available starting materials are well tolerated in this transition-metal-free protocol.

Eur. J. Org. Chem. 10.1002/ejoc.201601478 [Full Paper]

Metal-Free Photocatalytic Reductive Dehalogenation Using Visible-Light: A Time-Resolved Mechanistic Study

Metal-Free Photocatalytic Reductive Dehalogenation Using Visible-Light: A Time-Resolved Mechanistic Study

Rebeca Martinez-Haya, Miguel A. Miranda*, M. Luisa Marin*

The reductive dehalogenation of organic bromides has been achieved by using riboflavin (RF) as photocatalyst under visible-light irradiation. The viability of the different competing processes on the timescale of the corresponding RF excited states and RF radical anion were evaluated by time-resolved techniques. Thus, the key role of the RF radical anion has been proven.

Eur. J. Org. Chem. 10.1002/ejoc.201601494 [Full Paper]

Visible-Light-Mediated 5-exo-dig Cyclizations of Amidyl Radicals

Visible-Light-Mediated 5-exo-dig Cyclizations of Amidyl Radicals

Daniel Fernandez Reina, Elizabeth M. Dauncey, Sara P. Morcillo, Thomas D. Svejstrup, Mihai V. Popescu, James J. Douglas, Nadeem S. Sheikh*, Daniele Leonori*

Visible-light irradiation of electron-poor aryloxyamides in the presence of K2CO3 leads to the formation of amidyl radicals that undergo 5-exo-dig hydroamination–cyclization reactions to yield 5-methylene-pyrrolidinones.

Eur. J. Org. Chem. 10.1002/ejoc.201601607 [Communication]

Photocatalytic Trifluoromethylthiolation of Aromatic Alkenes Associated with Hydroxylation and Alkoxylation

Photocatalytic Trifluoromethylthiolation of Aromatic Alkenes Associated with Hydroxylation and Alkoxylation

Yanjie Li, Takashi Koike*, Munetaka Akita*

Activator-free: An additive-free photoredox-catalyzed trifluoromethylthiolation of aromatic alkenes has been developed. Trifluoromethanesulfenyl radical (.SCF3) is efficiently generated from a photocatalyst and an electrophilic triflouromethylthiolating reagent. This photoredox system induces a regioselective oxytrifluoromethylthiolation of carbon–carbon double bonds through catalytic processes without any activator.

Asian J. Org. Chem. 10.1002/ajoc.201600562 [Communication]

Zinc-Mediated syn-Selective Crotylation of N-Unsubstituted Imines

Zinc-Mediated syn-Selective Crotylation of N-Unsubstituted Imines

Won Jong Lee, Wook Jeong, Jaiwook Park*, Young Ho Rhee*

B-Ru-ZincA! The first example of a zinc-mediated stereoselective crotylation of N-unprotected imines has been developed. The imine was generated from an azide precursor by Ru catalysis under photolytic conditions. Interestingly, the reaction showed high syn-stereoselectivity. Mechanistic rationale is proposed to explain this selectivity.

Asian J. Org. Chem. 10.1002/ajoc.201600552 [Communication]

Metal-Free Visible-Light-Induced Trifluoromethylation Reactions

Metal-Free Visible-Light-Induced Trifluoromethylation Reactions

Gwi-Rim Park, Yeojin Choi, Myung Gil Choi, Suk-Kyu Chang, Eun Jin Cho*

Colors everywhere! Metal-free visible-light-induced trifluoromethylation reactions of alkenes, alkynes, and N-heterocycles with CF3I in the presence of Nile red, which acted as an organic photosensitizer under yellow LED irradiation, have been developed.

Asian J. Org. Chem. 10.1002/ajoc.201600541 [Communication]

Visible-Light Photoredox Decarboxylative Couplings

Visible-Light Photoredox Decarboxylative Couplings

Yunhe Jin, Hua Fu*

Good morning sunshine! Visible-light photoredox decarboxylative coupling reactions have become an important chemical transformation because of their wide substrate scope, mild reaction conditions, high efficiency, and practicability. Herein, we have summarized recent advances in this synthetic strategy, which include details regarding the formation of C−C and C−Y (Y=heteroatom) bonds.

Asian J. Org. Chem. 10.1002/ajoc.201600513 [Focus Review]

Photoredox Catalysis in Organophosphorus Chemistry

Photoredox Catalysis in Organophosphorus Chemistry

Kai Luo, Wen-Chao Yang, Lei Wu*

Soak up the sun! This review describes recent advances in the synthesis of organophosphorus compounds by employing methods such as photoredox catalysis, transition-metal complex/photoredox dual catalytic systems that incorporate phosphine ligands, and photoredox catalysis in the presence of organophosphorus compounds as organocatalysts.

Asian J. Org. Chem. 10.1002/ajoc.201600512 [Focus Review]

Porphyrin-Catalyzed Photochemical C-H Arylation of Heteroarenes

Porphyrin-Catalyzed Photochemical C-H Arylation of Heteroarenes

Katarzyna Rybicka-Jasińska, Burkhard König, Dorota Gryko*

Porphyrins are suitable photoredox catalysts for the direct C–H arylation of heteroarenes with aryl diazonium salts. The reaction involves photoelectron transfer from a porphyrin in its exited state to a diazonium salt.

Eur. J. Org. Chem. 10.1002/ejoc.201601518 [Communication]

A Photocatalytic Meerwein Approach to the Synthesis of Isochromanones and Isochromenones

A Photocatalytic Meerwein Approach to the Synthesis of Isochromanones and Isochromenones

Stefano Crespi, Stefanie Jäger, Burkhard König*, Maurizio Fagnoni*

A mild and facile photoredox approach towards synthetically interesting isochromanones and isochromenones is presented. The diazonium salts of various functionalised anthranilic acids have been converted by reaction with various alkenes into the desired bi- and tricyclic compounds in good to excellent yields.

Eur. J. Org. Chem. 10.1002/ejoc.201601458 [Full Paper]

Flavin-Mediated Visible-Light [2+2] Photocycloaddition of Nitrogen- and Sulfur-Containing Dienes

Flavin-Mediated Visible-Light [2+2] Photocycloaddition of Nitrogen- and Sulfur-Containing Dienes

Michael Jirásek, Karolína Straková, Tomáš Neveselý, Eva Svobodová, Zdeňka Rottnerová, Radek Cibulka*

The photoorganocatalytic [2+2] cycloaddition of dienes mediated by flavin derivative 1 and visible light affords a variety of aza and thia analogues of bicyclo[3.2.0]heptanes with high diastereoselectivities.

Eur. J. Org. Chem. 10.1002/ejoc.201601377 [Full Paper]

Visible-light-catalyzed Tandem Difluoroacetylation-Intramolecular Cyclization of 1,3-Diarylpropynones: Access to Difluoroacetylated Indenones

Visible-light-catalyzed Tandem Difluoroacetylation-Intramolecular Cyclization of 1,3-Diarylpropynones: Access to Difluoroacetylated Indenones

Savita B. Nagode, Atul Kumar Chaturvedi, Namrata Rastogi

Only visible light can do that: A mild and efficient synthesis of 3-aryl-2-difluoroacetyl indenones via visible-light-catalyzed difluoroacetylation of 1,3-diarylpropynones followed by intramolecular radical cyclization is reported. The reaction exhibits high regioselectivity and functional group tolerance.

Asian J. Org. Chem. 10.1002/ajoc.201600549 [Full Paper]

A Palladium/Light System Combined with Hanztsch Ester: Radical Vinylation of Alkyl Iodides with Vinyl Bromides

A Palladium/Light System Combined with Hanztsch Ester: Radical Vinylation of Alkyl Iodides with Vinyl Bromides

Shuhei Sumino, Ilhyong Ryu*

Radical vinylation of alkyl iodides with vinyl bromides proceeds smoothly with a combined Pd/light/Hanztsch ester system. In this reaction system, the Hanztsch ester acts as an effective reducing reagent of PdII to Pd0 that generates key alkyl radicals via single electron transfer (SET) with alkyl iodides upon photo-excitation.

Asian J. Org. Chem. 10.1002/ajoc.201600547 [Communication]

Synthesis of Tetrasubstituted Furans by Using Photoredox-Catalyzed Coupling of 2-Bromo-1,3-dicarbonyl Compounds with Silyl Enol Ethers

Synthesis of Tetrasubstituted Furans by Using Photoredox-Catalyzed Coupling of 2-Bromo-1,3-dicarbonyl Compounds with Silyl Enol Ethers

Yue-Yue Han, Yan-Yan Jiao, Daan Ren, Zhentao Hu, Sheng Shen*, Shouyun Yu*

Light Ir up: An efficient method for the synthesis of tetrasubstituted furans by using a photoredox-catalyzed coupling of 2-bromo-1,3-dicarbonyl compounds with silyl enol ethers has been developed.

Asian J. Org. Chem. 10.1002/ajoc.201600489 [Communication]

Visible-Light-Induced Intramolecular Chloroetherfication of Electron-Enriched Styrenes

Visible-Light-Induced Intramolecular Chloroetherfication of Electron-Enriched Styrenes

Run Lin, Hongnan Sun, Chao Yang*, Wujiong Xia*

Just give me the light! A novel visible-light-induced intramolecular chloroetherfication of electron-enriched styrenes is described. This approach provides a mild, alternative access to the synthesis of chlorinated tetrahydrofurans and tetrahydropyrans with high regio- and stereoselectivity.

Asian J. Org. Chem. 10.1002/ajoc.201600441 [Communication]

Visible-Light, Photoredox-Mediated Oxidative Tandem Nitroso-Diels-Alder Reaction of Arylhydroxylamines with Conjugated Dienes

Visible-Light, Photoredox-Mediated Oxidative Tandem Nitroso-Diels-Alder Reaction of Arylhydroxylamines with Conjugated Dienes

Veronica Santacroce, Raphael Duboc, Max Malacria, Giovanni Maestri, Geraldine Masson*

A visible-light, photoredox-mediated oxidative tandem nitroso-Diels–Alder reaction generates 3,6-dihydro-1,2-oxazines from arylhydroxylamines and dienes via intermediary nitrosoarenes in the presence of Ru(bpy)3Cl2 (bpy = 2,2′-bipyridine).

Eur. J. Org. Chem. 10.1002/ejoc.201601492 [Communication]

Sunflow: Sunlight Drives Fast and Green Photochemical Flow Reactions in Simple Microcapillary Reactors - Application to Photoredox and H-Atom-Transfer Chemistry

Sunflow: Sunlight Drives Fast and Green Photochemical Flow Reactions in Simple Microcapillary Reactors - Application to Photoredox and H-Atom-Transfer Chemistry

Alexander M. Nauth, Alexander Lipp, Benjamin Lipp, Till Opatz*

“Sunflow” – The combination of a microcapillary reactor and sunlight enables fast and green photoredox and H-atom-transfer reactions in continuous flow. Kinetic studies reveal high reaction rates with a simple and inexpensive reactor setup (less than 90 USD acquisition value).

Eur. J. Org. Chem. 10.1002/ejoc.201601394 [Communication]

Synthesis Of Biologically Active Bis(Indolyl)Methane Derivatives by Bisindole Alkylation of Tetrahydroisoquinolines with Visible-Light Induced Ring-Opening Fragmentation.

Synthesis Of Biologically Active Bis(Indolyl)Methane Derivatives by Bisindole Alkylation of Tetrahydroisoquinolines with Visible‐Light Induced Ring‐Opening Fragmentation.

Chia-Chueng Chen, Bor-Cherng Hong*, Wen-Shan Li*, Tzu-Ting Chang, Gene-Hsiang Lee

A visible-light photoredox catalyzed ring-opening functionalization of tetrahydroisoquinolines with bisindole alkylation has been developed and applied to synthesize biologically active bis(indolyl)methane derivatives that suppress cancer cell growth in human breast adenocarcinoma MDA-MB-231 cells, one of which has an important influence on cell migration.

Asian J. Org. Chem. 10.1002/ajoc.201600415 [Communication]

Aerobic Oxidation of Benzylic sp3 C−H Bonds through Cooperative Visible-Light Photoredox Catalysis of N-Hydroxyimide and Dicyanopyrazine

Aerobic Oxidation of Benzylic sp3 C−H Bonds through Cooperative Visible-Light Photoredox Catalysis of N-Hydroxyimide and Dicyanopyrazine

Xinfei Liu, Lu Lin, Xinyi Ye, Choon-Hong Tan, Zhiyong Jiang*

Two for the price of 1: A cooperative photoredox catalysis system between dicyanopyrazine-derived chromophore (DPZ) and N-hydroxyimide has been developed. This cooperative catalytic system facilitated the aerobic oxygenation of a series of benzylic sp3 C−H bonds through a photoredox pathway, affording valuable carbonyl compounds.

Asian J. Org. Chem. 10.1002/ajoc.201600426 [Communication]

Synthetic Method for the Preparation of Quinazolines by the Oxidation of Amines Using Singlet Oxygen

Synthetic Method for the Preparation of Quinazolines by the Oxidation of Amines Using Singlet Oxygen

Tomoaki Yamaguchi, Yukina Sugiura, Eiji Yamaguchi, Norihiro Tada, Akichika Itoh*

To dye for: We developed an efficient method for the synthesis of quinazolines by using singlet oxygen, which is generated by irradiation with visible light in the presence of rose bengal as a photosensitizer. Various substituted aldehydes were employed in this strategy that provided the corresponding quinazolines in moderate to excellent yields.

Asian J. Org. Chem. 10.1002/ajoc.201600431 [Communication]

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