scholarly journals Highly Acidic Conjugate‐Base‐Stabilized Carboxylic Acids Catalyze Enantioselective oxa‐Pictet–Spengler Reactions with Ketals

2019 ◽  
Vol 132 (5) ◽  
pp. 2044-2048
Author(s):  
Zhengbo Zhu ◽  
Minami Odagi ◽  
Chenfei Zhao ◽  
Khalil A. Abboud ◽  
Helmi Ulrika Kirm ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Conjugate Base

Conductimetric and potentiometric investigation of effect of acidity on formation of homoconjugates in acetonitrile solvent

1990 ◽  
Vol 68 (5) ◽  
pp. 674-678 ◽  
Author(s):  
Turgut Gündüz ◽  
Esma Kiliç ◽  
Güleren Özkan ◽  
Muhammed F. Awaad ◽  
Mustafa Tastekin
Keyword(s):  
Carboxylic Acids ◽  
Potentiometric Titration ◽  
Major Part ◽  
Nitrogen Atmosphere ◽  
Nonaqueous Media ◽  
Potentiometric Titrations ◽  
End Point ◽  
Titration Curves ◽  
Aliphatic Carboxylic Acids ◽  
Conjugate Base

In the present work, 11 aromatic and nine aliphatic carboxylic acids, namely benzoic, 2-nitrobenzoic, 3-nitrobenzoic, 4-nitrobenzoic, 2,4-dinitrobenzoic, 3,5-dinitrobenzoic, 2-aminobenzoic, 3-aminobenzoic, 4-aminobenzoic, o-phthalic, salicylic, formic, acetic, monochloroacetic, dichloroacetic, trichloroacetic, propionic, n-butyric, caprylic, and myristic acids, were titrated conductimetrically and potentiometrically with triethylamine in acetonitrile solvent, under a nitrogen atmosphere, at 25 °C. Closer investigation of the conductimetric titration curves of these acids showed that the acidity of an acid, rather than the basicity of its conjugate base, plays a major part in the formation of homoconjugate ions, at least in acetonitrile solvent. If the acid is strong enough, there is a maximum before the experimental end point at about the half-neutralization point. To determine the minimum strength for an acid to show this maximum before the end point, all acids were also titrated potentiometrically. It was found that those acids which have half-neutralization potentials over −85 mV give a strong homoconjugation reaction and show a maximum before the experimental end point. Moreover, the acids that show maxima before the experimental end point in the conductimetric titration also show rather well-shaped potentiometric titration curves. Keywords: nonaqueous media, conductimetric titrations, potentiometric titrations, titration in acetonitrile, acidity and homoconjugation.

scholarly journals Highly Acidic Conjugate‐Base‐Stabilized Carboxylic Acids Catalyze Enantioselective oxa‐Pictet–Spengler Reactions with Ketals

2020 ◽  
Vol 59 (5) ◽  
pp. 2028-2032 ◽  
Author(s):  
Zhengbo Zhu ◽  
Minami Odagi ◽  
Chenfei Zhao ◽  
Khalil A. Abboud ◽  
Helmi Ulrika Kirm ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Conjugate Base

Modular Design of Chiral Conjugate-Base-Stabilized Carboxylic Acids: Catalytic Enantioselective [4 + 2] Cycloadditions of Acetals

2020 ◽  
Vol 142 (36) ◽  
pp. 15252-15258 ◽  
Author(s):  
Zhengbo Zhu ◽  
Minami Odagi ◽  
Nantamon Supantanapong ◽  
Weici Xu ◽  
Jaan Saame ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Modular Design ◽  
Conjugate Base

A convenient preparative method for 1,4-diketones from carboxylic acids

1977 ◽  
Vol 27 (1) ◽  
pp. 117-120
Author(s):  
Shoji Watanabe ◽  
Tsutomu Fujita ◽  
Kyoichi Suga ◽  
Haruhiko Abe
Keyword(s):  
Carboxylic Acids ◽  
Preparative Method

Probing The Resolution of 2-Alkoxy and 2-Aryloxy Carboxylic Acids

2006 ◽  
Author(s):  
Jason Eames ◽  
Ewan Boyd ◽  
Sameer Chavda
Keyword(s):  
Carboxylic Acids

Ligand-Enabled γ-C(sp3)–H Olefination of Free Carboxylic Acids

2020 ◽  
Author(s):  
Kiron Kumar Ghosh ◽  
Alexander Uttry ◽  
Francesca Ghiringhelli ◽  
Arup Mondal ◽  
Manuel van Gemmeren
Keyword(s):  
Reaction Mechanism ◽  
Carboxylic Acids ◽  
Michael Addition ◽  
Kinetic Studies ◽  
Wide Range ◽  
Palladium Catalyzed

We report the ligand enabled C(sp3)–H activation/olefination of free carboxylic acids in the γ-position. Through an intramolecular Michael-addition, δ-lactones are obtained as products. Two distinct ligand classes are identified that enable the challenging palladium-catalyzed activation of free carboxylic acids in the γ-position. The developed protocol features a wide range of acid substrates and olefin reaction partners and is shown to be applicable on a preparatively useful scale. Insights into the underlying reaction mechanism obtained through kinetic studies are reported.<br>

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