scholarly journals How bulky ligands control the chemoselectivity of Pd-catalyzed N-arylation of ammonia

2020 ◽  
Vol 11 (4) ◽  
pp. 1017-1025 ◽  
Author(s):  
Seoung-Tae Kim ◽  
Suyeon Kim ◽  
Mu-Hyun Baik
Keyword(s):  
Design Principle ◽  
Steric Effect ◽  
Reaction Pathway ◽  
Mechanistic Study ◽  
Bulky Ligands

Steric bulk has been recognized as a central design principle for ligands in the widely utilized Buchwald–Hartwig amination. This mechanistic study reveals how this steric effect manipulates the reaction pathway and determines the chemoselectivity.

Mechanistic Study of Metal–Ligand Cooperativity in Mn(II)-Catalyzed Hydroborations: Hemilabile SNS Ligand Enables Metal Hydride-Free Reaction Pathway

ACS Catalysis ◽  
2021 ◽  
pp. 9043-9051
Author(s):  
Matthew R. Elsby ◽  
Mina Son ◽  
Changjin Oh ◽  
Jessica Martin ◽  
Mu-Hyun Baik ◽  
...  
Keyword(s):  
Metal Hydride ◽  
Reaction Pathway ◽  
Mechanistic Study ◽  
Sns Ligand ◽  
Metal Ligand

Cyanide-Mediated Synthesis of Sulfones and Sulfonamides from Vinyl Sulfones

Synlett ◽  
2019 ◽  
Vol 31 (05) ◽  
pp. 455-458
Author(s):  
Tamal Roy ◽  
Ji-Woong Lee
Keyword(s):  
High Selectivity ◽  
Reaction Pathway ◽  
Secondary Amines ◽  
Mechanistic Study ◽  
Facile Synthesis ◽  
Primary And Secondary Amines ◽  
In Situ Generation ◽  
High Yields

We report a facile synthesis of sulfones, β-keto sulfones, and sulfonamides from vinyl sulfones via an addition–elimination sequence where in situ generation of nucleophilic sulfinate ion is mediated by cyanide. The use vinyl sulfones renders high selectivity for S-alkylation to produce sulfones in high yields. In the presence of N-bromosuccinimide, primary and secondary amines underwent sulfonamide formation. A preliminary mechanistic study showed the formation of acrylonitrile as an innocent byproduct, without interfering with the desired reaction pathway while generating a sulfinate nucleophile.

scholarly journals Mechanism of the Arene-Limited Nondirected C–H Activation of Arenes with Palladium

2020 ◽  
Author(s):  
Philipp Wedi ◽  
Mirxan Farizyan ◽  
Klaus Bergander ◽  
Christian Mück-Lichtenfeld ◽  
Manuel van Gemmeren
Keyword(s):  
Palladium Catalysts ◽  
Method Development ◽  
Design Principle ◽  
Active Species ◽  
Synthetic Methods ◽  
Mechanistic Study ◽  
Directing Group ◽  
Rate Limiting ◽  
Complex Organic

Palladium catalysts have recently been discovered that enable the directing group-free C–H activation and functionalization of arenes without requiring an excess of the arene substrate. By overcoming this long standing challenge, the resulting synthetic methods have now become suitable for the functionalization of complex organic molecules. The key to success in several of these transformations has been the use of two complementary ligands, an N-acyl amino acid and an N-heterocycle. Further applications of this design principle will likely require the guidance by a profound mechanistic understanding. This prompted us to engage in a detailed experimental and computational mechanistic study of the dual ligandenabled C–H activation of arenes. Based on comprehensive kinetic experiments, (CID-)MS and DOSY-NMR measurements, and DFT calculations we find that a 1:1:1 complex of palladium and the two ligands is the active species that enables a partially rate-limiting concerted C–H activation as part of a PdII/Pd0-cycle. Our study highlights the importance of catalyst speciation and allows us to rationalize the role of each ligand as well as the observed regioselectivities. These findings are expected to be highly useful for further method development using this powerful class of catalysts.

New reduction mechanism of CO dimer by hydrogenation to C2H4 on a Cu(100) surface: theoretical insight into the kinetics of the elementary steps

RSC Advances ◽  
2015 ◽  
Vol 5 (117) ◽  
pp. 96281-96289 ◽  
Author(s):  
Lihui Ou ◽  
Wenqi Long ◽  
Yuandao Chen ◽  
Junling Jin
Keyword(s):  
Reaction Pathway ◽  
Mechanistic Study ◽  
Reduction Mechanism ◽  
Elementary Steps ◽  
Kinetics Of ◽  
Theoretical Insight ◽  
Insight Into

An alternative reaction pathway for the production of C2H4 through the OCCO* intermediate from CO dimerization is provided in this mechanistic study.

Reaction of Thiols with N-Bonded Sulfenamide Complexes of Cobalt(III):  Steric Effect and Reaction Pathway

2005 ◽  
Vol 44 (2) ◽  
pp. 293-299 ◽  
Author(s):  
Margaret J. Sisley ◽  
Michael J. Ferguson ◽  
Robert B. Jordan
Keyword(s):  
Steric Effect ◽  
Reaction Pathway

MECHANISTIC STUDY OF THE REACTIONS OF SULFUR TRIOXIDE WITH HYDROGEN HALIDES TO FORM SUPERACID AND SURVEY OF HALO-SULFONIC ACID STRENGTH

2005 ◽  
Vol 04 (spec01) ◽  
pp. 623-638 ◽  
Author(s):  
KEVIN H. WEBER ◽  
JULIE A. HARRIS ◽  
LAURA J. LARSON ◽  
FU-MING TAO ◽  
SHUJIN LI ◽  
...  
Keyword(s):  
Sulfonic Acid ◽  
Sulfur Trioxide ◽  
Density Functional ◽  
Reaction Pathway ◽  
Mechanistic Study ◽  
Functional Theory ◽  
Hydrogen Halides ◽  
Donor Acceptor ◽  
Hydrolysis Of ◽  
Equilibrium Geometries

The reaction mechanisms for the formations of halo-sulfonic acids from sulfur trioxide and hydrogen halides are investigated using density functional theory. Two channels of reaction are considered: the binary SO 3 + HX reaction pathway and the ternary SO 3 + 2 HX pathway. Equilibrium geometries, harmonic frequencies, and relative energies of the reactant, transition state, and product clusters are calculated at the B3LYP/6-311++G** level. Hydrogen fluoride was found to have a particularly strong interaction with SO 3, forming an electron donor acceptor complex. Similarities to the hydrolysis of SO 3 to form sulfuric acid are discussed and the relative acidities of the halo-sulfonic acid series are evaluated and compared in the same context to sulfuric and perchloric acids.

scholarly journals Mechanism of the Arene-Limited Nondirected C–H Activation of Arenes with Palladium

2020 ◽  
Author(s):  
Philipp Wedi ◽  
Mirxan Farizyan ◽  
Klaus Bergander ◽  
Christian Mück-Lichtenfeld ◽  
Manuel van Gemmeren
Keyword(s):  
Palladium Catalysts ◽  
Method Development ◽  
Design Principle ◽  
Active Species ◽  
Synthetic Methods ◽  
Mechanistic Study ◽  
Directing Group ◽  
Rate Limiting ◽  
Complex Organic

Palladium catalysts have recently been discovered that enable the directing group-free C–H activation and functionalization of arenes without requiring an excess of the arene substrate. By overcoming this long standing challenge, the resulting synthetic methods have now become suitable for the functionalization of complex organic molecules. The key to success in several of these transformations has been the use of two complementary ligands, an N-acyl amino acid and an N-heterocycle. Further applications of this design principle will likely require the guidance by a profound mechanistic understanding. This prompted us to engage in a detailed experimental and computational mechanistic study of the dual ligandenabled C–H activation of arenes. Based on comprehensive kinetic experiments, (CID-)MS and DOSY-NMR measurements, and DFT calculations we find that a 1:1:1 complex of palladium and the two ligands is the active species that enables a partially rate-limiting concerted C–H activation as part of a PdII/Pd0-cycle. Our study highlights the importance of catalyst speciation and allows us to rationalize the role of each ligand as well as the observed regioselectivities. These findings are expected to be highly useful for further method development using this powerful class of catalysts.

scholarly journals Mechanism of the Arene-Limited Nondirected C–H Activation of Arenes with Palladium: A Combined Experimental and Theoretical Study

2019 ◽  
Author(s):  
Philipp Wedi ◽  
Klaus Bergander ◽  
Christian Mück-Lichtenfeld ◽  
Manuel van Gemmeren
Keyword(s):  
Palladium Catalysts ◽  
Method Development ◽  
Design Principle ◽  
Active Species ◽  
Synthetic Methods ◽  
Mechanistic Study ◽  
Directing Group ◽  
Rate Limiting ◽  
Complex Organic

Recently, synthetic methods have been discovered which enable the directing group-free C–H activation of arenes with palladium-catalysts and do not require an excess of the arene substrate. By overcoming this long standing challenge, such methods have now become suitable for the functionalization of complex organic molecules. The key to success in several of these transformations has been the use of two complementary ligands, an N-acyl amino acid and an Nheterocycle. Further applications of this design principle will likely require the guidance by a profound mechanistic understanding. This prompted us to engage in a detailed experimental and computational mechanistic study of the dual ligand enabled C–H activation of arenes. Based on comprehensive kinetic experiments, (CID-)MS, (DOSY-)NMR, and DFT calculations we find that a 1:1:1 complex of palladium and the two ligands is indeed the active species that enables a partially rate-limiting concerted C–H activation as part of a Pd<sup>0</sup>/Pd<sup>II</sup>-cycle. Our study highlights the importance of catalyst speciation and allows us to rationalize the role of each ligand as well as the observed regioselectivities. These findings are expected to be highly useful for further method development using this powerful class of catalysts.

Mechanistic study of proliferation induced by Angelica sinensis in gastric epithelial cells

2001 ◽  
Vol 120 (5) ◽  
pp. A145-A145
Author(s):  
C CHO ◽  
Y YE ◽  
E LIU ◽  
V SHIN ◽  
N SHAM
Keyword(s):  
Epithelial Cells ◽  
Mechanistic Study ◽  
Angelica Sinensis ◽  
Gastric Epithelial Cells
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