Derailing Dehydroquinate Synthase by Introducing a Stabilizing Stereoelectronic Effect in a Reaction Intermediate

1997 ◽  
Vol 62 (24) ◽  
pp. 8582-8585 ◽  
Author(s):  
Emily J. Parker ◽  
John R. Coggins ◽  
Chris Abell
Keyword(s):  
Stereoelectronic Effect ◽  
Reaction Intermediate ◽  
Dehydroquinate Synthase

Conformational Stability, FMO, NMR, MEP and NBO Analysis of 2,5-Di-methyl-2,5-bis(methylthio)-1,4-dithiane and Dimethoxy compounds by DFT Approach

2021 ◽  
Vol 17 ◽  
Author(s):  
Nasrin Masnabadi
Keyword(s):  
Computational Methods ◽  
Electrostatic Potential ◽  
Conformational Stability ◽  
Nbo Analysis ◽  
Dft Methods ◽  
Geometrical Properties ◽  
Stereoelectronic Effect ◽  
Nmr Parameters ◽  
Electron Transfers ◽  
Stability Energy

Abstract: Conformational behaviors of 2,5-dimethoxy-2,5-dimethyl-1,4-dithiane (compound 1) and 2,5-dimethyl-2,5-bis (methylthio)-1,4-dithiane (compound 2) investigated by computational methods including B3LYP/6-311+G** and M06-2X/6-311+G** levels of theory and NBO analysis. The stereoelectronic effect of axial, axial (ax, ax) and equatorial, equa-torial (eq, eq) conformations were studied using NBO analysis. Using NBO analysis, the values of the stereoelectronic effects were calculated through the energy of stability associated with the electron transfers of compounds 1 and 2. The results showed that the eq, eq conformations of the studied compounds were more stable than their corresponding ax, ax conformations, and LP2X→σS1-C2 and LP2S→σ*C2-X electron transfers play important roles in the conformational be-havior of the studied compounds. The main purpose of the present work was to study the effects of stereoelectronic inter-actions and steric on the conformational superiority of the di-methoxy (compound 1) and di-thiomethyl compounds (com-pound 2). Thus, the values of resonance stability energy, non-diagonal elements, and orbital populations were investigated. Also, active electrophilic and nucleophilic centers were identified using fronting orbitals analysis obtained by DFT methods. The electrostatic potential maps of the title compounds were investigated at the B3LYP/6-311+G* level of theory. All of the NMR parameters and geometrical properties of both compounds were determined in this study.

Preparation and Characterization of Oxoiron(IV) Chlorin Complexes as the First Models for a Reaction Intermediate in the Catalytic Cycle of Cytochrome d

1994 ◽  
Vol 116 (2) ◽  
pp. 634-641 ◽  
Author(s):  
Shinji Ozawa ◽  
Yoshihito Watanabe ◽  
Satoru Nakashima ◽  
Teizo Kitagawa ◽  
Isao Morishima
Keyword(s):  
Catalytic Cycle ◽  
Reaction Intermediate ◽  
Cytochrome D

scholarly journals Theoretical insight on the treatment of β-hexachlorocyclohexane waste through alkaline dehydrochlorination

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alicia Bescós ◽  
Clara I. Herrerías ◽  
Zoel Hormigón ◽  
José Antonio Mayoral ◽  
Luis Salvatella
Keyword(s):  
Density Functional ◽  
Kinetic Studies ◽  
Alkaline Treatment ◽  
Functional Study ◽  
Reaction Intermediates ◽  
Preferential Formation ◽  
Reaction Intermediate ◽  
Rate Determining Step ◽  
Dehydrochlorination Reaction ◽  
Theoretical Results

AbstractThe occurrence of 4.8–7.2 million tons of hexachlorocyclohexane (HCH) isomers stocked in dumpsites around the world constitutes a huge environmental and economical challenge because of their toxicity and persistence. Alkaline treatment of an HCH mixture in a dehydrochlorination reaction is hampered by the low reactivity of the β-HCH isomer (HCl elimination unavoidably occurring through syn H–C–C–Cl arrangements). More intriguingly, the preferential formation of 1,2,4-trichlorobenzene in the β-HCH dehydrochlorination reaction (despite the larger thermodynamical stability of the 1,3,5-isomer) has remained unexplained up to now, though several kinetic studies had been reported. In this paper, we firstly show a detailed Density Functional study on all paths for the hydroxide anion-induced elimination of β-HCH through a three-stage reaction mechanism (involving two types of reaction intermediates). We have now demonstrated that the first reaction intermediate can follow several alternative paths, the preferred route involving abstraction of the most acidic allylic hydrogen which leads to a second reaction intermediate yielding only 1,2,4-trichlorobenzene as the final reaction product. Our theoretical results allow explaining the available experimental data on the β-HCH dehydrochlorination reaction (rate-determining step, regioselectivity, instability of some reaction intermediates).

Zur Erzeugung von Silaethenen des Typus R2Si=CH(SiR3 ) und R2Si=CH2 durch thermische Salzeliminierung sowie zur Kenntnis von R2Si=CH(SitBu3) (R = Me, tBu ) / On the Generation of Silaethenes of the Types R2Si=CH(SiR3) and R2Si=CH2 by Thermal Salt Elimination and on the Knowledge of R2Si=CH(SitBu3) (R = Me, tBu)

1996 ◽  
Vol 51 (12) ◽  
pp. 1744-1760 ◽  
Author(s):  
Nils Wiberg ◽  
Ch. M. M. Finger ◽  
T. Passler ◽  
S. Wagner ◽  
K. Polborn
Keyword(s):  
Diels Alder ◽  
X Ray ◽  
Reaction Intermediate

The generation of silaethenes Me2Si=CH(SiMe3) (1), Me2Si=CH(SitBu3) (2), tBuMeSi=CH(SitBu3) (3), and tBu2Si=CH2 (4) from metal organyls >SiX-CM< (X = Br, F; M = Na, Li) by elimination of MX is investigated. The metal organyls are prepared from >SiX-CBr< and RM (R = tBu3Si, nBu, Ph) by Br/M exchange (for preparation of >SiX-CBr< cf. Scheme 1). Only the sterically overcrowded silaethenes 2 and 3. generated from Me2SiF-CHNa(SitBu3) and tBuMeSiF-CHNa(SitBu3), have been identified by trapping with isobutene and dimethylbutadiene under formation of ene and Diels-Alder adducts. Analogous products are not found from Me2SiBr-CHNa(SiMe3) and tBu2-SiBr-CH2-Li. In the absence of trapping agents, compounds 1, 2, and 3 form cyclodimers. A reaction intermediate of the formation of 1 × 1 has been isolated and the structures of 2 × 2 and 3 × 3 have been solved by X-ray analysis. No dimer is observed for 4. In this case compounds are formed which may be interpreted as insertion products of 4 into the CLi bond of the precursor.

scholarly journals Structural evidence for a reaction intermediate mimic in the active site of a sulfite dehydrogenase

2020 ◽  
Vol 56 (68) ◽  
pp. 9850-9853
Author(s):  
Ahmed Djeghader ◽  
Melanie Rossotti ◽  
Saleh Abdulkarim ◽  
Frédéric Biaso ◽  
Guillaume Gerbaud ◽  
...  
Keyword(s):  
Active Site ◽  
Spectroscopic Evidence ◽  
Reaction Intermediate

We provide structural and spectroscopic evidence for a molybdenum–phosphate adduct mimicking a proposed reaction intermediate in the active site of a prokaryotic sulfite oxidizing enzyme.

Sign in / Sign up

Export Citation Format

Share Document