Accelerating Unimolecular Decarboxylation by Preassociated Acid Catalysis in Thiamin-Derived Intermediates:  Implicating Brønsted Acids as Carbanion Traps in Enzymes

2006 ◽  
Vol 128 (49) ◽  
pp. 15856-15864 ◽  
Author(s):  
Ronald Kluger ◽  
Glenn Ikeda ◽  
Qingyan Hu ◽  
Pengpeng Cao ◽  
Joel Drewry
Keyword(s):  
Acid Catalysis ◽  
Bronsted Acids

scholarly journals Recent Advances in Transition-Metal-Free (4+3)-Annulations

Synthesis ◽  
2021 ◽  
Author(s):  
Heather Lam ◽  
Mark Lautens ◽  
Xavier Abel-Snape ◽  
Martin F. Köllen
Keyword(s):  
Transition Metal ◽  
Boronic Acid ◽  
Lewis Acids ◽  
Acid Catalysis ◽  
Heterocyclic Carbenes ◽  
Bronsted Acids ◽  
Metal Free ◽  
Previous Review ◽  
Dual Activation ◽  
Metal Catalyzed

Abstract(4+3)-Annulations are incredibly versatile reactions which combine a 4-atom synthon and a 3-atom synthon to form both 7-membered carbocycles as well as heterocycles. We have previously reviewed transition-metal-catalyzed (4+3)-annulations. In this review, we will cover examples involving bases, NHCs, phosphines, Lewis and Brønsted acids as well as some rare examples of boronic acid catalysis and photocatalysis. In analogy to our previous review, we exclude annulations involving cyclic dienes like furan, pyrrole, cyclohexadiene or cyclopentadiene, as Chiu, Harmata, Fernándes and others have recently published reviews encompassing such substrates. We will however discuss the recent additions (2010–2020) to the literature on (4+3)-annulations involving other types of 4-atom-synthons.1 Introduction2 Bases3 Annulations Using N-Heterocyclic Carbenes3.1 N-Heterocyclic Carbenes (NHCs)3.2 N-Heterocyclic Carbenes and Base Dual-Activation4 Phosphines5 Acids5.1 Lewis Acids5.2 Brønsted Acids6 Boronic Acid Catalysis and Photocatalysis7 Conclusion

scholarly journals Brønsted acid catalysis of photosensitized cycloadditions

2020 ◽  
Vol 11 (3) ◽  
pp. 856-861 ◽  
Author(s):  
Evan M. Sherbrook ◽  
Hoimin Jung ◽  
Dasol Cho ◽  
My-Hyun Baik ◽  
Tehshik P. Yoon
Keyword(s):  
Energy Transfer ◽  
Acid Catalysis ◽  
Reorganization Energy ◽  
Transfer Reactions ◽  
Bronsted Acids ◽  
Bronsted Acid ◽  
Triplet Energy ◽  
Dft Computations ◽  
Brönsted Acid ◽  
Triplet Energy Transfer

Brønsted acids can catalyze triplet energy transfer reactions, and DFT computations suggest the unexpected importance of reorganization energy for catalysis.

Brønsted acids of anionic chiral Co(iii) complexes as catalysts for the stereoselective synthesis of cis-4-aminofuranobenzopyrans

2017 ◽  
Vol 15 (43) ◽  
pp. 9077-9080 ◽  
Author(s):  
Hua-Jie Jiang ◽  
Kun Liu ◽  
Jing Wang ◽  
Na Li ◽  
Jie Yu
Keyword(s):  
Acid Catalysis ◽  
Stereoselective Synthesis ◽  
Bronsted Acids ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid ◽  
Povarov Reaction ◽  
Bronsted Acid Catalysis

A highly enantioselective interrupted Povarov reaction of salicylaldimines was developed, through the elegant Brønsted acid catalysis of anionic chiral Co(iii) complexes.

scholarly journals Tandem Lewis/Brønsted homogeneous acid catalysis: conversion of glucose to 5-hydoxymethylfurfural in an aqueous chromium(iii) chloride and hydrochloric acid solution

2015 ◽  
Vol 17 (10) ◽  
pp. 4725-4735 ◽  
Author(s):  
T. Dallas Swift ◽  
Hannah Nguyen ◽  
Andrzej Anderko ◽  
Vladimiros Nikolakis ◽  
Dionisios G. Vlachos
Keyword(s):  
Hydrochloric Acid ◽  
Acid Solution ◽  
Hydrochloric Acid Solution ◽  
Acid Catalysis ◽  
Bronsted Acids ◽  
Homogeneous Acid

Optimizing the concentrations of Lewis and Brønsted acids maximizes the 5-hydroxymethylfurfural yield from glucose in a single pot.

Cobalt/Lewis Acid Catalysis for Hydrocarbofunctionalization of Alkynes via Cooperative C–H Activation

2020 ◽  
Author(s):  
Chang-Sheng Wang ◽  
Sabrina Monaco ◽  
Anh Ngoc Thai ◽  
Md. Shafiqur Rahman ◽  
Chen Wang ◽  
...  
Keyword(s):  
Catalytic System ◽  
Lewis Acid ◽  
Hydrogen Transfer ◽  
Acid Catalysis ◽  
Rate Limiting Step ◽  
Site Selectivity ◽  
Set Up ◽  
Site Selective ◽  
First Time ◽  
Rate Limiting

A catalytic system comprised of a cobalt-diphosphine complex and a Lewis acid (LA) such as AlMe3 has been found to promote hydrocarbofunctionalization reactions of alkynes with Lewis basic and electron-deficient substrates such as formamides, pyridones, pyridines, and azole derivatives through site-selective C-H activation. Compared with known Ni/LA catalytic system for analogous transformations, the present catalytic system not only feature convenient set up using inexpensive and bench-stable precatalyst and ligand such as Co(acac)3 and 1,3-bis(diphenylphosphino)propane (dppp), but also display distinct site-selectivity toward C-H activation of pyridone and pyridine derivatives. In particular, a completely C4-selective alkenylation of pyridine has been achieved for the first time. Mechanistic stidies including DFT calculations on the Co/Al-catalyzed addition of formamide to alkyne have suggested that the reaction involves cleavage of the carbamoyl C-H bond as the rate-limiting step, which proceeds through a ligand-to-ligand hydrogen transfer (LLHT) mechanism leading to an alkyl(carbamoyl)cobalt intermediate.

One-Pot Synthesis and Conformational Analysis of 6-Membered Cyclic Iodonium Salts

2020 ◽  
Author(s):  
Lucien Caspers ◽  
Julian Spils ◽  
Mattis Damrath ◽  
Enno Lork ◽  
Boris Nachtsheim
Keyword(s):  
Conformational Analysis ◽  
Bronsted Acids ◽  
One Pot ◽  
Benzyl Alcohols ◽  
Iodonium Salts ◽  
Efficient Approach ◽  
One Pot Synthesis ◽  
Diaryliodonium Salts

In this article we describe an efficient approach for the synthesis of cyclic diaryliodonium salts. The method is based on benzyl alcohols as starting materials and consists of an Friedel-Crafts-arylation/oxidation sequence. Besides a deep optimization, particluar focusing on the choice and ratios of the utilized Bronsted-acids and oxidants, we explore the substrate scope of this transformation. We also discuss an interesting isomerism of cyclic iodonium salts substituted with aliphatic substituents at the bridge head carbon. <br>

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