An Efficient Deprotection of 2,6-Bis(trifluoromethyl)phenylboronic Esters via Catalytic Protodeboronation Using Tetrabutyl­ammonium Fluoride

Synlett ◽  
2019 ◽  
Vol 30 (20) ◽  
pp. 2300-2304
Author(s):  
Sari Urata ◽  
Shinya Nojima ◽  
Kazuishi Makino ◽  
Naoyuki Shimada
Keyword(s):  
Catalytic Amount ◽  
Organic Transformations ◽  
Tetrabutylammonium Fluoride ◽  
Protective Groups

We herein describe an efficient deprotection of 2,6-bis(trifluoromethyl)phenylboronic esters, which serve as effective protective groups for 1,2- or 1,3-diols in various organic transformations, via protodeboronation by using a catalytic amount of tetrabutylammonium fluoride (TBAF).

scholarly journals Tetrabutylammonium Bromide (TBAB) Catalyzed Synthesis of Bioactive Heterocycles

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5918
Author(s):  
Bimal Krishna Banik ◽  
Bubun Banerjee ◽  
Gurpreet Kaur ◽  
Shivam Saroch ◽  
Rajat Kumar
Keyword(s):  
Phase Transfer ◽  
Tetrabutylammonium Bromide ◽  
Catalytic Amount ◽  
Coupling Reactions ◽  
Efficient Synthesis ◽  
Organic Transformations ◽  
Co Catalyst ◽  
Oxidation Reduction ◽  
Recent Developments ◽  
Significant Attention

During the last two decades, tetrabutylammonium bromide (TBAB) has gained significant attention as an efficient metal-free homogeneous phase-transfer catalyst. A catalytic amount of TBAB is sufficient to catalyze various alkylation, oxidation, reduction, and esterification processes. It is also employed as an efficient co-catalyst for numerous coupling reactions. It has also acted as an efficient zwitterionic solvent in many organic transformations under molten conditions. In this review, we have summarized the recent developments on TBAB-catalyzed protocols for the efficient synthesis of various biologically promising heterocyclic scaffolds.

Reversing Reactivity: Stereoselective Desulfurative β-O-Glycosylation of Anomeric Thiosugars with Carboxylic Acids Under Copper or Cobalt Catalysis

2019 ◽  
Author(s):  
Samir Messaoudi ◽  
Nedjwa Bennai ◽  
Amelie Chabrier ◽  
Maha Fatthalla ◽  
Expédite Yen-Pon ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Late Stage ◽  
Catalytic Amount ◽  
Broad Scope ◽  
Wide Range ◽  
Glycosylation Reaction

We have discovered a new mode of reactivity of 1-thiosugars in the presence of Cu(II) or Co(II) for a stereoselective <i>O</i>-glycosylation reaction. The process involves the use of a catalytic amount of Cu(acac)2 or Co(acac)2 and Ag2CO3 as an oxidant in α,α,α-trifluorotoluene (TFT). Moreover, this protocol turned out to have a broad scope, allowing to prepare a wide range of com-plex substituted <i>O</i>-glycoside esters in good to excellent yields with an exclusive β-selectivity. The late-stage modification of phar-maceuticals by this method was also demonstrated.

Visible Light-Mediated Oxidative Debenzylation

2020 ◽  
Author(s):  
Cristian Cavedon ◽  
Eric T. Sletten ◽  
Amiera Madani ◽  
Olaf Niemeyer ◽  
Peter H. Seeberger ◽  
...  
Keyword(s):  
Reaction Time ◽  
Visible Light ◽  
Functional Groups ◽  
Continuous Flow ◽  
Protecting Groups ◽  
Benzyl Ether ◽  
Complex Molecules ◽  
Protective Groups ◽  
Benzyl Ethers ◽  
Harsh Conditions

Protecting groups are key in the synthesis of complex molecules such as carbohydrates to distinguish functional groups of similar reactivity. The harsh conditions required to cleave stable benzyl ether protective groups are not compatible with many other protective and functional groups. The mild, visible light-mediated debenzylation disclosed here renders benzyl ethers orthogonal protective groups. Key to success is the use of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as stoichiometric or catalytic photooxidant such that benzyl ethers can be cleaved in the presence of azides, alkenes, and alkynes. The reaction time for this transformation can be reduced from hours to minutes in continuous flow. <br>

Catalytic Synthesis of Cyclic Guanidines via Hydrogen Atom Transfer and Radical-Polar Crossover

2020 ◽  
Author(s):  
Shunya Ohuchi ◽  
Hiroki Koyama ◽  
Hiroki Shigehisa
Keyword(s):  
Hydrogen Atom ◽  
Functional Group ◽  
Hydrogen Atom Transfer ◽  
Catalytic Synthesis ◽  
Membered Ring ◽  
Biologically Active ◽  
Atom Transfer ◽  
Powerful Method ◽  
Protective Groups ◽  
The Common

A catalytic synthesis of cyclic guanidines, which are found in many biologically active compounds and natu-ral products, was developed, wherein transition-metal hydrogen atom transfer and radical-polar crossover were employed. This mild and functional-group tolerant process enabled the cyclization of alkenyl guanidines bearing common protective groups, such as Cbz and Boc. This powerful method not only provided the common 5- and 6-membered rings but also an unusual 7-membered ring. The derivatization of the products afforded various heterocycles. We also investigated the se-lective cyclization of mono-protected or hetero-protected (TFA and Boc) alkenyl guanidines and their further derivatiza-tions.

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.

Arylboronic Acids in Self-condensation of Glucosamines Forming Deoxyfructosazine, Catalysts or Reagents?

2019 ◽  
Author(s):  
Meifeng Wang ◽  
Gan Zhu ◽  
Yiqun Li ◽  
Liuqun Gu
Keyword(s):  
Molecular Recognition ◽  
Boric Acid ◽  
Boronic Acid ◽  
Catalytic Mechanism ◽  
Organic Transformations ◽  
Food Industries ◽  
Arylboronic Acids ◽  
Excess Amount ◽  
Phenyl Boronic Acid ◽  
Boron Acid

Arylboronic acids were widely used as efficient catalysts in direct amide formation and other organic transformations. Surprisingly, reports on their use as catalysts in carbohydrates synthesis are very rare even though boron acid-diol complexation was extensively investigated in molecular recognition for saccharides and so on. Here we developed an efficient arylboronic acids catalyzed dimerization of glucosamines forming deoxyfructosazine which is important compound in pharmaceutical and food industries, against a commonly held belief that excess amount of phenyl boronic acid (or boric acid) is a must. A catalytic mechanism was also proposed and arylboronic acids instead of their boronates was identified as catalysts.

The Synthesis and Application of Functionalized Mesoporous Silica SBA-15 as Heterogeneous Catalyst in Organic Synthesis

2020 ◽  
Vol 24 ◽  
Author(s):  
Ghodsi Mohammadi Ziarani ◽  
Shima Roshankar ◽  
Fatemeh Mohajer ◽  
Alireza Badiei
Keyword(s):  
Mesoporous Silica ◽  
Heterogeneous Catalyst ◽  
Organic Synthesis ◽  
Lewis Acid ◽  
Heterogeneous Catalysts ◽  
Organic Transformations ◽  
Functionalized Mesoporous Silica ◽  
Silica Nanomaterials ◽  
Wide Range ◽  
Target Molecules

Abstract:: Mesoporous silica nanomaterials provide an extraordinary advantage for making new and superior heterogeneous catalysts because of their surface silanol groups. The functionalized mesoporous SBA-15, such as acidic, basic, BrÖnsted, lewis acid, and chiral catalysts, are used for a wide range of organic synthesis. The importance of the chiral ligands, which were immobilized on the SBA-15, was mentioned in this review to achieve chiral products as valuable target molecules. Herein, their synthesis and application in different organic transformations are reviewed from 2016 till date 2020.

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