scholarly journals Computational Investigation on the Enantioselective Copper(I)-Catalyzed Addition of Enynes to Ketones

2018 ◽  
Author(s):  
Hanwei Li ◽  
Mingliang Luo ◽  
Guohong Tao ◽  
Song Qin
Keyword(s):  
Reaction Mechanism ◽  
Steric Hindrance ◽  
Phenyl Ring ◽  
Dft Method ◽  
Catalytic Cycle ◽  
Computational Investigation ◽  
Enantioselective Addition ◽  
Chiral Centers ◽  
Chiral Systems

Computational investigations on the BPE-ligated Cu-catalysed enantioselective addition of enynes to ketones were performed with DFT method. Two BPE-CuMes catalysts, BPE-CuMes and (S,S)-Ph-BPE–CuMes, were employed to probe the reaction mechanism with the emphasis on stereoselectivity. The calculations on the BPE-CuMes system indicate that the actvie metallized enyne intermediate acts as the catalyst for the catalytic cycle. The catalytic cycle involves two steps: 1) the ketone addition to the alkene moiety of the metallized enyne; 2) the metallization of enyne followed by the release of product with the recovery of the active metallized enyne intermediate. The first step accounts for the distribution of the products, and therefore is the stereo-controlling step in chiral systems. In the chiral (S,S)-Ph-BPE–CuMes system, the steric hindrance is vital for the distribution of products and responsible for the stereoselectivity of this reaction. The steric hindrance between the phenyl ring of the two substrates and groups at the chiral centers in the ligand skeleton is identified as the original of the stereoselectivity for the titled reaction.

scholarly journals Theoretical Calculations on the Mechanism of Enantioselective Copper(I)-Catalyzed Addition of Enynes to Ketones

Catalysts ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 359 ◽  
Author(s):  
Hanwei Li ◽  
Mingliang Luo ◽  
Guohong Tao ◽  
Song Qin
Keyword(s):  
Density Functional Theory ◽  
Steric Hindrance ◽  
Phenyl Ring ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Dft Method ◽  
Catalytic Cycle ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Chiral Systems

Computational investigations on the bisphospholanoethane (BPE)-ligated Cu-catalyzed enantioselective addition of enynes to ketones were performed with the density functional theory (DFT) method. Two BPE-mesitylcopper (CuMes) catalysts, BPE-CuMes and (S,S)-Ph-BPE–CuMes, were employed to probe the reaction mechanism with the emphasis on stereoselectivity. The calculations on the BPE-CuMes system indicate that the active metallized enyne intermediate acts as the catalyst for the catalytic cycle. The catalytic cycle involves two steps: (1) ketone addition to the alkene moiety of the metallized enyne; and (2) metallization of the enyne followed by the release of product with the recovery of the active metallized enyne intermediate. The first step accounts for the distribution of the products, and therefore is the stereo-controlling step in chiral systems. In the chiral (S,S)-Ph-BPE–CuMes system, the steric hindrance is vital for the distribution of products and responsible for the stereoselectivity of this reaction. The steric hindrance between the phenyl ring of the two substrates and groups at the chiral centers in the ligand skeleton is identified as the original of the stereoselectivity for the titled reaction.

scholarly journals Exploring the full catalytic cycle of rhodium(i)–BINAP-catalysed isomerisation of allylic amines: a graph theory approach for path optimisation

2017 ◽  
Vol 8 (6) ◽  
pp. 4475-4488 ◽  
Author(s):  
Takayoshi Yoshimura ◽  
Satoshi Maeda ◽  
Tetsuya Taketsugu ◽  
Masaya Sawamura ◽  
Keiji Morokuma ◽  
...  
Keyword(s):  
Graph Theory ◽  
Reaction Mechanism ◽  
Catalytic Cycle ◽  
Theory Approach ◽  
Allylic Amines ◽  
Reaction Route ◽  
Reaction Method ◽  
Mapping Strategy ◽  
Global Reaction ◽  
Induced Reaction

The reaction mechanism of the cationic rhodium(i)–BINAP complex catalysed isomerisation of allylic amines was explored using the artificial force induced reaction method with the global reaction route mapping strategy.

scholarly journals Etomidate and Etomidate Analog Binding and Positive Modulation of γ-Aminobutyric Acid Type A Receptors

2018 ◽  
Vol 129 (5) ◽  
pp. 959-969 ◽  
Author(s):  
Megan McGrath ◽  
Zhiyi Yu ◽  
Selwyn S. Jayakar ◽  
Celena Ma ◽  
Mansi Tolia ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
Gabaa Receptors ◽  
Binding Sites ◽  
Phenyl Ring ◽  
Type A ◽  
Binding Pocket ◽  
Aminobutyric Acid ◽  
Substituent Group ◽  
Acid Type ◽  
Site Selective

Abstract Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New Background Naphthalene-etomidate, an etomidate analog containing a bulky phenyl ring substituent group, possesses very low γ-aminobutyric acid type A (GABAA) receptor efficacy and acts as an anesthetic-selective competitive antagonist. Using etomidate analogs containing phenyl ring substituents groups that range in volume, we tested the hypothesis that this unusual pharmacology is caused by steric hindrance that reduces binding to the receptor’s open state. Methods The positive modulatory potencies and efficacies of etomidate and phenyl ring–substituted etomidate analogs were electrophysiology defined in oocyte-expressed α1β3γ2L GABAA receptors. Their binding affinities to the GABAA receptor’s two classes of transmembrane anesthetic binding sites were assessed from their abilities to inhibit receptor labeling by the site-selective photolabels 3[H]azi-etomidate and tritiated R-5-allyl-1-methyl-5-(m-trifluoromethyl-diazirynylphenyl) barbituric acid. Results The positive modulatory activities of etomidate and phenyl ring–substituted etomidate analogs progressively decreased with substituent group volume, reflecting significant decreases in both potency (P = 0.005) and efficacy (P < 0.0001). Affinity for the GABAA receptor’s two β+ − α– anesthetic binding sites similarly decreased with substituent group volume (P = 0.003), whereas affinity for the receptor’s α+ – β–/γ+ – β– sites did not (P = 0.804). Introduction of the N265M mutation, which is located at the β+ − α– binding sites and renders GABAA receptors etomidate-insensitive, completely abolished positive modulation by naphthalene-etomidate. Conclusions Steric hindrance selectively reduces phenyl ring–substituted etomidate analog binding affinity to the two β+ − α– anesthetic binding sites on the GABAA receptor’s open state, suggesting that the binding pocket where etomidate’s phenyl ring lies becomes smaller as the receptor isomerizes from closed to open.

scholarly journals Deoxydehydration of vicinal diols by homogeneous catalysts: a mechanistic overview

2019 ◽  
Vol 6 (11) ◽  
pp. 191165 ◽  
Author(s):  
Kayla A. DeNike ◽  
Stefan M. Kilyanek
Keyword(s):  
Reaction Mechanism ◽  
Product Distribution ◽  
Catalytic Cycle ◽  
Reaction Conditions ◽  
Homogeneous Catalysts ◽  
Commodity Chemicals ◽  
Reduction Methods ◽  
Vicinal Diols ◽  
Catalyst Systems

Deoxydehydration (DODH) is an important reaction for the upconversion of biomass-derived polyols to commodity chemicals such as alkenes and dienes. DODH can be performed by a variety of early metal-oxo catalysts incorporating Re, Mo and V. The varying reduction methods used in the DODH catalytic cycle impact the product distribution, reaction mechanism and the overall yield of the reaction. This review surveys the reduction methods commonly used in homogeneous DODH catalyst systems and their impacts on yield and reaction conditions.

scholarly journals The Interaction between Graphene and Oxygen Atom

Open Physics ◽  
2016 ◽  
Vol 14 (1) ◽  
pp. 690-694 ◽  
Author(s):  
Yifan Hao ◽  
Xuejun Zhao ◽  
Xuedan Song ◽  
Hongjiang Li ◽  
Xiaobing Zhu ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Oxygen Atom ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Density Function ◽  
Energy Surface ◽  
Function Theory ◽  
Dft Method ◽  
Density Function Theory ◽  
Basis Set

AbstractBased on the density function theory (DFT) method, the interaction between the graphene and oxygen atom is simulated by the B3LYP functional with the 6-31G basis set. Due to the symmetry of graphene (C54H18, D6h), a representative patch is put forward to represent the whole graphene to simplify the description. The representative patch on the surface is considered to gain the potential energy surface (PES). By the calculation of the PES, four possible stable isomers of the C54H18-O radical can be obtained. Meanwhile, the structures and energies of the four possible stable isomers, are further investigated thermodynamically, kinetically, and chemically. According to the transition states, the possible reaction mechanism between the graphene and oxygen atom is given.

2,6-Di-tert-butyl-4-(phenyliminomethyl)phenol

2006 ◽  
Vol 62 (4) ◽  
pp. o1455-o1456
Author(s):  
Xi-Long Yan ◽  
Li-Gong Chen ◽  
Tao Zeng
Keyword(s):  
Molecular Structure ◽  
Hydrogen Bond ◽  
Benzene Ring ◽  
Dihedral Angle ◽  
Hydroxy Group ◽  
Steric Hindrance ◽  
Phenyl Ring ◽  
Tert Butyl

In the title molecular structure, C21H27NO, the dihedral angle between the phenyl ring and the benzene ring planes is 63.28 (9) Å. It appears that the hydroxy group is prevented from forming a hydrogen bond because of steric hindrance by the tert-butyl groups.

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