Photocatalytic Alkylation of Pyrroles and Indoles with α-Diazo Esters

2019 ◽  
Author(s):  
Łukasz Ciszewski ◽  
Jakub Durka ◽  
Dorota Gryko
Keyword(s):  
Aromatic Compounds ◽  
Reaction Pathway ◽  
Alkylating Agents ◽  
Catalytic Amount ◽  
Radical Formation ◽  
Reaction Selectivity ◽  
Diazo Esters ◽  
Electron Withdrawing Substituents

This article describes direct photoalkylation of electron-rich aromatic compounds with diazo compoiunds. C-2 alkylated indoles and pyrroles are obtained with good yields even though the photocatalyst (Ru(bpy)3Cl2) loading is as low as 0.075 mol %. For substrates bearing electron-withdrawing substituents the addition of a catalytic amount of N,N-dimethyl-4-methoxyaniline is required. Both EWG-EWG and EWG-EDG substituted diazo esters are suitable as alkylating agents. The reaction selectivity and mechanistic experiments suggest that carbenes/carbenoid intermediates are not involved in the reaction pathway, instead radical formation is proposed.

Photocatalytic Alkylation of Pyrroles and Indoles with α-Diazo Esters

2019 ◽  
Author(s):  
Łukasz Ciszewski ◽  
Jakub Durka ◽  
Dorota Gryko
Keyword(s):  
Aromatic Compounds ◽  
Reaction Pathway ◽  
Alkylating Agents ◽  
Catalytic Amount ◽  
Radical Formation ◽  
Reaction Selectivity ◽  
Diazo Esters ◽  
Electron Withdrawing Substituents

This article describes direct photoalkylation of electron-rich aromatic compounds with diazo compoiunds. C-2 alkylated indoles and pyrroles are obtained with good yields even though the photocatalyst (Ru(bpy)3Cl2) loading is as low as 0.075 mol %. For substrates bearing electron-withdrawing substituents the addition of a catalytic amount of N,N-dimethyl-4-methoxyaniline is required. Both EWG-EWG and EWG-EDG substituted diazo esters are suitable as alkylating agents. The reaction selectivity and mechanistic experiments suggest that carbenes/carbenoid intermediates are not involved in the reaction pathway, instead radical formation is proposed.

Indium(III) triflate — a catalyst for greener aromatic alkylation reactions

2013 ◽  
Vol 91 (12) ◽  
pp. 1262-1265 ◽  
Author(s):  
Ryan Mack ◽  
Grant Askins ◽  
Jacob Lowry ◽  
Nathan Hurley ◽  
Perry C. Reeves
Keyword(s):  
Ionic Liquid ◽  
Aromatic Compounds ◽  
Energy Efficient ◽  
Alkylating Agents ◽  
Catalytic Amount ◽  
Significant Loss ◽  
Primary Alcohols ◽  
Tertiary Alcohols ◽  
Alkylation Reactions ◽  
Environmentally Friendly Method

An environmentally friendly method for alkylating aromatic compounds with simple alcohols in the presence of a catalytic amount of indium(III) triflate is reported. Ionic liquids are used as solvents and energy-efficient heating is provided by microwave radiation. Good yields are obtained with benzyl, secondary, and tertiary alcohols. Simple primary alcohols are not effective alkylating agents under these conditions. With tertiary alcohols, activated aromatic compounds such as toluene and anisole must be used to obtain good yields. The catalyst, which is immobilized in a water-insoluble ionic liquid, can be easily recycled without significant loss of activity.

A Metal-Free and Ionic Liquid-Catalyzed Aerobic Oxidative Bromination in Water

2015 ◽  
Vol 68 (3) ◽  
pp. 513 ◽  
Author(s):  
Jian Wang ◽  
Shu-Bin Chen ◽  
Shu-Guang Wang ◽  
Jing-Hua Li
Keyword(s):  
Ionic Liquid ◽  
Aromatic Compounds ◽  
Hydrobromic Acid ◽  
Bromine Atom ◽  
Catalytic Amount ◽  
Atom Economy ◽  
First Report ◽  
Metal Free ◽  
Oxidative Bromination

A metal-free aerobic oxidative bromination of aromatic compounds in water has been developed. Hydrobromic acid is used as a bromine source and 2-methylpyridinium nitrate ionic liquid is used as a recyclable catalyst. Water is used as the reaction mediate. This is the first report of aerobic oxidative bromination using only catalytic amount of metal-free catalyst. This system shows not only high bromine atom economy, but also high bromination selectivity. The possible mechanism and the role of the catalyst in this system have also been discussed.

Studies toward the total synthesis of naturally occurring pyranonaphthoquinones from Ventilago harmandiana

2012 ◽  
Vol 84 (6) ◽  
pp. 1435-1443 ◽  
Author(s):  
Sopanat Kongsriprapan ◽  
Chutima Kuhakarn ◽  
Pramchai Deelertpaiboon ◽  
Kanda Panthong ◽  
Patoomratana Tuchinda ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Gallic Acid ◽  
Lithium Chloride ◽  
Aromatic Compounds ◽  
Catalytic Amount ◽  
Enantioselective Synthesis ◽  
Synthetic Route ◽  
Endemic Plant ◽  
Naturally Occurring ◽  
Trimethyl Aluminum

The enantioselective synthesis of a naturally occurring pyranonaphthoquinone isolated from a Thai endemic plant, Ventilago harmandiana, has been achieved. L-Rhamnose and gallic acid were used as the starting materials. A new C-1-glycosidation of L-rhamnal with trimethyl aluminum in the presence of a catalytic amount of ytterbium(III) triflate was developed. A new reagent, PhSCF2H/SnCl4, for the formylation of partially deactivated and hindered aromatic compounds has been introduced. Phenylthiophthalide was used efficiently as a cycloannulating agent in the Hauser cycloannulation reaction, employing slightly excess lithium t-butoxide as a base with a catalytic amount of lithium chloride. The synthetic route developed is applicable for the synthesis of other analogues with substituents at the aromatic and pyran rings.

Silica gel Supported Boric tri-Sulfuric Anhydride (SiO2-BTSA): An Efficient Catalytic System for the Synthesis of Phloroglucide Analogs as Antimicrobial Agents

2021 ◽  
Vol 18 (4) ◽  
pp. 419-428
Author(s):  
Rahele Bargebid ◽  
Ali Khalafi-Nezhad ◽  
Kamiar Zomorodian ◽  
Mahkameh Moradi ◽  
Soghra Khabnadideh
Keyword(s):  
Silica Gel ◽  
Aromatic Compounds ◽  
Antimicrobial Agents ◽  
Biological Activities ◽  
Catalytic Amount ◽  
Biologically Active ◽  
Sulfuric Anhydride ◽  
Chemical Structures ◽  
Broth Microdilution Method

Background: Polyhydroxy aromatic compounds are one of the most important classes of phenolic compounds with different biological activities. Some important and biologically active phenol-based compounds have also been isolated from nature. Methods: An efficient procedure for the synthesis of polyhydroxy aromatic compounds (phloroglucide analogs) is described. In this procedure, a reaction took place between different 4-substituted phenols and 2,6-bis(hydroxymethyl) phenols. The reactions proceed in the presence of catalytic amount of silica gel supported boric tri-sulfuric anhydride (SiO2-BTSA) in excellent yields. Results: 16 compounds were synthesized (I1-I16). Chemical structures of all the compounds were confirmed by spectroscopic methods. We optimized the chemical reactions in the presence of different acidic catalysts, different solvents and also different temperatures. A catalytic amount of SiO2-BTSA in dichloroethane (DCE) was the best condition. Some of the synthesized compounds were screened for their antimicrobial activities. Antifungal and antibacterial activities of the synthesized compounds were evaluated by broth microdilution method as recommended by CLSI. Some of the tested compounds showed good in vitro biological properties. Conclusion: Our active compounds could introduce as good candidates for further studies as antimicrobial agents.

Effective and regioselective iodination of arenes using iron(III) nitrate in the presence of tungstophosphoric acid

2005 ◽  
Vol 83 (10) ◽  
pp. 1808-1811 ◽  
Author(s):  
Mohammad Jafarzadeh ◽  
Kamal Amani ◽  
Farzad Nikpour
Keyword(s):  
Aromatic Compounds ◽  
Good Yield ◽  
Catalytic Amount ◽  
Molecular Iodine ◽  
Tungstophosphoric Acid ◽  
Iron Nitrate ◽  
Nitrate Nonahydrate ◽  
Iron Nitrate Nonahydrate

An easy, cheap, and effective method for iodination of various aromatic compounds takes place with molecular iodine and iron nitrate nonahydrate as the oxidant in the presence of a catalytic amount of tungstophosphoric acid in dichloromethane, with good yield and high regioselectivity under very mild conditions.Key words: iodination, arenes, iodine, iron(III) nitrate, tungstophosphoric acid.

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