scholarly journals Aryl Amination Using Soluble Weak Base Enabled by a Water-Assisted Mechanism

2020 ◽  
Vol 142 (47) ◽  
pp. 20030-20039
Author(s):  
Sii Hong Lau ◽  
Peng Yu ◽  
Liye Chen ◽  
Christina B. Madsen-Duggan ◽  
Michael J. Williams ◽  
...  
Keyword(s):  
Weak Base ◽  
Aryl Amination

scholarly journals Aryl Amination with Soluble Weak Base Enabled by a Water-Assisted Mechanism

2020 ◽  
Author(s):  
Sii Hong Lau ◽  
Peng Yu ◽  
Liye Chen ◽  
Christina B. Madsen-Duggan ◽  
Michael Williams ◽  
...  
Keyword(s):  
Secondary Amines ◽  
Coupling Reactions ◽  
Weak Base ◽  
Bond Forming ◽  
Cross Coupling Reactions ◽  
Aryl Amination ◽  
Catalytic Intermediates ◽  
Palladium Catalyzed ◽  
Poorly Soluble ◽  
Soluble Base

Amination of aryl halides has become one of the most commonly practiced C–N bond-forming reactions in pharmaceutical and laboratory synthesis. The widespread use of strong or poorly soluble inorganic bases for amine activation nevertheless complicates the compatibility of this important reaction class with sensitive substrates as well as applications in flow and automated synthesis, to name a few. We report a palladium-catalyzed C–N coupling using Et<sub>3</sub>N as a weak, soluble base, which allows a broad substrate scope that includes bromo- and chloro(hetero)arenes, primary anilines, secondary amines, and amide type nucleophiles together with tolerance for a range of base-sensitive functional groups. Mechanistic data have established a unique pathway for these reactions in which water serves multiple beneficial roles. In particular, ionization of a neutral catalytic intermediate via halide displacement by H<sub>2</sub>O generates, after proton loss, a coordinatively-unsaturated Pd–OH species that can bind amine substrate triggering intramolecular N–H heterolysis. This water-assisted pathway operates efficiently with even weak terminal bases, such as Et<sub>3</sub>N. The use of a simple, commercially available ligand, PAd<sub>3</sub>, is key to this water-assisted mechanism by promoting coordinative unsaturation in catalytic intermediates responsible for the heterolytic activation of strong element-hydrogen bonds, which enables broad compatibility of carbon-heteroatom cross-coupling reactions with sensitive substrates and functionality.

scholarly journals Aryl Amination with Soluble Weak Base Enabled by a Water-Assisted Mechanism

2020 ◽  
Author(s):  
Sii Hong Lau ◽  
Peng Yu ◽  
Liye Chen ◽  
Christina B. Madsen-Duggan ◽  
Michael Williams ◽  
...  
Keyword(s):  
Secondary Amines ◽  
Coupling Reactions ◽  
Weak Base ◽  
Bond Forming ◽  
Cross Coupling Reactions ◽  
Aryl Amination ◽  
Catalytic Intermediates ◽  
Palladium Catalyzed ◽  
Poorly Soluble ◽  
Soluble Base

Amination of aryl halides has become one of the most commonly practiced C–N bond-forming reactions in pharmaceutical and laboratory synthesis. The widespread use of strong or poorly soluble inorganic bases for amine activation nevertheless complicates the compatibility of this important reaction class with sensitive substrates as well as applications in flow and automated synthesis, to name a few. We report a palladium-catalyzed C–N coupling using Et<sub>3</sub>N as a weak, soluble base, which allows a broad substrate scope that includes bromo- and chloro(hetero)arenes, primary anilines, secondary amines, and amide type nucleophiles together with tolerance for a range of base-sensitive functional groups. Mechanistic data have established a unique pathway for these reactions in which water serves multiple beneficial roles. In particular, ionization of a neutral catalytic intermediate via halide displacement by H<sub>2</sub>O generates, after proton loss, a coordinatively-unsaturated Pd–OH species that can bind amine substrate triggering intramolecular N–H heterolysis. This water-assisted pathway operates efficiently with even weak terminal bases, such as Et<sub>3</sub>N. The use of a simple, commercially available ligand, PAd<sub>3</sub>, is key to this water-assisted mechanism by promoting coordinative unsaturation in catalytic intermediates responsible for the heterolytic activation of strong element-hydrogen bonds, which enables broad compatibility of carbon-heteroatom cross-coupling reactions with sensitive substrates and functionality.

Cr(VI) RETENTION CAPACITY AND SELECTIVITY OF SOME STRONG AND WEAK BASE ANION EXCHANGERS

2004 ◽  
Vol 3 (3) ◽  
pp. 221-230 ◽  
Author(s):  
Ion Untea ◽  
Cristina Orbeci ◽  
Elena Tudorache ◽  
Violeta Neagu
Keyword(s):  
Weak Base ◽  
Anion Exchangers ◽  
Retention Capacity

Adenovirus uncoating and nuclear establishment are not affected by weak base amines.

1996 ◽  
Vol 70 (6) ◽  
pp. 3470-3477 ◽  
Author(s):  
E Rodríguez ◽  
E Everitt
Keyword(s):  
Weak Base

scholarly journals Weak base g-functions and metrizability of topological spaces

2011 ◽  
Vol 158 (2) ◽  
pp. 238-243
Author(s):  
Er-Guang Yang ◽  
Wei-Xue Shi
Keyword(s):  
Topological Spaces ◽  
Weak Base

scholarly journals Weaker cousins of Ramsey's theorem over a weak base theory

2021 ◽  
pp. 103028
Author(s):  
Marta Fiori-Carones ◽  
Leszek Aleksander Kołodziejczyk ◽  
Katarzyna W. Kowalik
Keyword(s):  
Weak Base ◽  
Ramsey's Theorem ◽  
Base Theory ◽  
Ramsey’S Theorem

Effects of Surface Properties and Solvent PH Values on the Adsorption/Desorption Abilities of Mesoporous SBA-15 to Methylene Blue Molecules

2012 ◽  
Vol 518-523 ◽  
pp. 352-355
Author(s):  
Hui Liu ◽  
Hong Liang Li ◽  
Meng Xue Wang ◽  
Jing Jing Sang ◽  
Xiu Song Zhao
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Surface Properties ◽  
Weak Base ◽  
Adsorption Ability ◽  
Ph Values ◽  
Model Molecule ◽  
Adsorption Desorption

Methylene blue (MB) was used as model molecule to investigate the effects of surface properties and solvent pH values on the adsorption and desorption (or release) behaviors of mesoporous SBA-15 materials. It was found that the treatment of SBA-15 with a pH 7.8 aqueous solution can enhance the adsorption rate and capacity in comparison with the pristine SBA-15. The effect of pH values on MB releasing from the weak base treated SBA-15 and the pristine one have been studied and been compared in pH values range from 0.5 to 7.0. Both of them showed a maximum releasing rate at about pH 2 and all of the treated SBA-15 samples showed a higher releasing quantity than the pristine ones. The influence mechanisms of base treatment on the adsorption ability and that of pH values on the releasing properties of SBA-15 samples have been analyzed and been discussed based on the composition, the morphology, the surface area and pore size distribution and adsorption/desorption measurements.

Recyclable polymer-supported Pd catalysts for aryl amination reactions

2005 ◽  
Vol 46 (43) ◽  
pp. 7363-7366 ◽  
Author(s):  
Meritxell Guinó ◽  
King Kuok (Mimi) Hii
Keyword(s):  
Pd Catalysts ◽  
Aryl Amination ◽  
Supported Pd Catalysts ◽  
Polymer Supported ◽  
Supported Pd

The absorption of carbon dioxide by weak base ion exchange resins

AIChE Journal ◽  
1970 ◽  
Vol 16 (4) ◽  
pp. 609-614 ◽  
Author(s):  
Oscar W. Weber ◽  
Irving F. Miller ◽  
Harry P. Gregor
Keyword(s):  
Carbon Dioxide ◽  
Ion Exchange ◽  
Ion Exchange Resins ◽  
Weak Base ◽  
Exchange Resins
Sign in / Sign up

Export Citation Format

Share Document