DMSO/iodine-catalyzed oxidative C–Se/C–S bond formation: a regioselective synthesis of unsymmetrical chalcogenides with nitrogen- or oxygen-containing arenes

2016 ◽  
Vol 6 (9) ◽  
pp. 3087-3098 ◽  
Author(s):  
Sumbal Saba ◽  
Jamal Rafique ◽  
Antonio L. Braga
Keyword(s):  
Bond Activation ◽  
Bond Formation ◽  
Solvent Free ◽  
Regioselective Synthesis ◽  
Metal Free ◽  
Different Types ◽  
Free Iodine

A convenient metal-free and solvent-free iodine-catalyzed regioselective greener protocol to access different types of unsymmetrical chalcogenides with nitrogen- or oxygen-containing arenes through oxidative C–Se/C–S formation via direct C(sp2)–H bond activation was developed.

Iodine-mediated C–N and C–S bond formation: regioselective synthesis of benzo[4,5]imidazo[2,1-b]thiazoles

2017 ◽  
Vol 41 (1) ◽  
pp. 75-80 ◽  
Author(s):  
Sethurajan Ambethkar ◽  
Muthalu Vellimalai ◽  
Vediappen Padmini ◽  
Nattamai Bhuvanesh
Keyword(s):  
Reaction Time ◽  
Intramolecular Cyclization ◽  
Simple Procedure ◽  
Bond Formation ◽  
Molecular Iodine ◽  
Regioselective Synthesis ◽  
Thiazole Derivatives ◽  
Short Reaction Time ◽  
Metal Free

The regioselective synthesis of benzo[4,5]imidazo[2,1-b]thiazole derivatives via amination (C–N) and intramolecular cyclization (C–S) reactions in the presence of molecular iodine has been reported. This method is base and metal free and features inexpensive catalysts, with a simple procedure and a short reaction time.

Non-Classical Amide Bond Formation: Transamidation and Amidation of Activated Amides and Esters by Selective N–C/O–C Cleavage

Synthesis ◽  
2020 ◽  
Vol 52 (18) ◽  
pp. 2579-2599 ◽  
Author(s):  
Michal Szostak ◽  
Guangchen Li
Keyword(s):  
Transition Metal ◽  
Bond Activation ◽  
Bond Formation ◽  
Amide Bond ◽  
Acyl Transfer ◽  
Metal Free ◽  
Amide Bond Formation ◽  
New Methods ◽  
Formidable Challenge ◽  
Tetrahedral Intermediates

In the past several years, tremendous advances have been made in non-classical routes for amide bond formation that involve transamidation and amidation reactions of activated amides and esters. These new methods enable the formation of extremely valuable amide bonds via transition-metal-catalyzed, transition-metal-free, or metal-free pathways by exploiting chemoselective acyl C–X (X = N, O) cleavage under mild conditions. In a broadest sense, these reactions overcome the formidable challenge of activating C–N/C–O bonds of amides or esters by rationally tackling nN → π*C=O delocalization in amides and nO → π*C=O donation in esters. In this account, we summarize the recent remarkable advances in the development of new methods for the synthesis of amides with a focus on (1) transition-metal/NHC-catalyzed C–N/C–O bond activation, (2) transition-metal-free highly selective cleavage of C–N/C–O bonds, (3) the development of new acyl-transfer reagents, and (4) other emerging methods.1 Introduction2 Transamidation of Amides2.1 Transamidation by Metal–NHC Catalysis (Pd–NHC, Ni–NHC)2.2 Transition-Metal-Free Transamidation via Tetrahedral Intermediates2.3 Reductive Transamidation2.4 New Acyl-Transfer Reagents2.5 Tandem Transamidations3 Amidation of Esters3.1 Amidation of Esters by Metal–NHC Catalysis (Pd–NHC, Ni–NHC)3.2 Transition-Metal-Free Amidation of Esters via Tetrahedral Intermediates3.3 Reductive Amidation of Esters4 Transamidations of Amides by Other Mechanisms5 Conclusions and Outlook

Oxidative organophotoredox catalysis: a regioselective synthesis of 2-nitro substituted imidazopyridines and 3-substituted indoles, initiated by visible light

2016 ◽  
Vol 40 (11) ◽  
pp. 9694-9701 ◽  
Author(s):  
Snehlata Yadav ◽  
Madhulika Srivastava ◽  
Pratibha Rai ◽  
Bhartendu Pati Tripathi ◽  
Anu Mishra ◽  
...  
Keyword(s):  
Visible Light ◽  
Visible Light Irradiation ◽  
Room Temperature ◽  
Bond Formation ◽  
Light Irradiation ◽  
Regioselective Synthesis ◽  
Metal Free

Intramolecular C–N heterocyclization and C–C bond formation under visible light irradiation at room temperature was accomplished with a metal-free photoredox catalyst.

Ionic Liquid Catalyzed Efficient Regioselective Synthesis of 1,4- Disubstituted 1,2,3-Triazoles under Metal and Solvent free Conditions

2020 ◽  
Vol 07 ◽  
Author(s):  
Abid H. Banday ◽  
Victor J. Hruby
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Solvent Free ◽  
Regioselective Synthesis ◽  
Chromatographic Separations ◽  
One Pot ◽  
Green Protocol ◽  
Metal Free ◽  
Organic Azides ◽  
Solvent Free Conditions

Background: Unprecedented, one-pot regioselective synthesis of 1,4-disubstituted 1,2,3-triazoles through azide- aldehyde (3+2) organo-click cycloaddition under metal and solvent-free conditions, is described. Objective: Solvent and metal free synthesis of biologically and industrially important triazoles. Methods: Efficient and high yielding synthesis of products avoiding the tedious high solvent workups and chromatographic separations. The synthesis doesn’t involve the routine acetylenes which are very costly but instead cheaper starting materials like aldehydes and organic azides are used. Results: Green protocol based on the catalysis through Ionic Liquids which simultaneously act as solvents. The products are obtained in good to excellent yields in hassle free synthesis. Conclusion: Efficient and green synthesis of structurally and biologically important triazoles.

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