ChemInform Abstract: Synthetic Studies on the Role of Substituents at C-3 Position on C3-C4 Bond Cleavage of β-Lactam Ring: Convenient Route for Diastereoselective Synthesis of Pyridin-2-ones.

ChemInform ◽  
2013 ◽  
Vol 44 (18) ◽  
pp. no-no
Author(s):  
Pardeep Singh ◽  
Parvesh Singh ◽  
Kewal Kumar ◽  
Vipan Kumar ◽  
Mohinder P. Mahajan ◽  
...  
Keyword(s):  
Bond Cleavage ◽  
Diastereoselective Synthesis ◽  
Lactam Ring ◽  
Convenient Route ◽  
Synthetic Studies

Synthetic Studies on the Role of Substituents at C-3 Position on C3-C4 Bond Cleavage of β-Lactam Ring: Convenient Route for Diastereoselective Synthesis of Pyridin-2-ones

Heterocycles ◽  
2012 ◽  
Vol 86 (2) ◽  
pp. 1301 ◽  
Author(s):  
Mohinder P. Mahajan ◽  
Pardeep Singh ◽  
Parvesh Singh ◽  
Kewal Kumar ◽  
Vipan Kumar ◽  
...  
Keyword(s):  
Bond Cleavage ◽  
Diastereoselective Synthesis ◽  
Lactam Ring ◽  
Convenient Route ◽  
Synthetic Studies

Metal-Metal Cooperative Bond Activation by Heterobimetallic Alkyl, Aryl, and Acetylide PtII/CuI Complexes

2020 ◽  
Author(s):  
Shubham Deolka ◽  
Orestes Rivada Wheelaghan ◽  
Sandra Aristizábal ◽  
Robert Fayzullin ◽  
Shrinwantu Pal ◽  
...  
Keyword(s):  
Alkyl Group ◽  
Bond Activation ◽  
Bond Cleavage ◽  
Terminal Alkyne ◽  
Alkyl Aryl ◽  
Metal Metal ◽  
The Stability ◽  
Selective Formation ◽  
Organoplatinum Compounds

We report selective formation of heterobimetallic PtII/CuI complexes that demonstrate how facile bond activation processes can be achieved by altering reactivity of common organoplatinum compounds through their interaction with another metal center. The interaction of the Cu center with Pt center and with a Pt-bound alkyl group increases the stability of PtMe2 towards undesired rollover cyclometalation. The presence of the CuI center also enables facile transmetalation from electron-deficient tetraarylborate [B(ArF)4]- anion and mild C-H bond cleavage of a terminal alkyne, which was not observed in the absence of an electrophilic Cu center. The DFT study indicates that the role of Cu center acts as a binding site for alkyne substrate, while activating its terminal C-H bond.

Mechanisms of ATP to cAMP Conversion Catalyzed by the Mammalian Adenylyl Cyclase: A Role of Magnesium Coordination Shells and Proton Wires

2019 ◽  
Author(s):  
Bella Grigorenko ◽  
Igor Polyakov ◽  
Alexander Nemukhin
Keyword(s):  
Adenylyl Cyclase ◽  
Bond Cleavage ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Md Simulations ◽  
Coordination Shell ◽  
Energy Profile ◽  
One Step ◽  
Type V

<p>We report a mechanism of adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP) conversion by the mammalian type V adenylyl cyclase revealed in molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) simulations. We characterize a set of computationally derived enzyme-substrate (ES) structures showing an important role of coordination shells of magnesium ions in the solvent accessible active site. Several stable six-fold coordination shells of Mg<sub>A</sub><sup>2+ </sup>are observed in MD simulations of ES complexes. In the lowest energy ES conformation, the coordination shell of Mg<sub>A</sub><sup>2+ </sup>does not include the O<sub>δ1</sub> atom of the conserved Asp440 residue. Starting from this conformation, a one-step reaction mechanism is characterized which includes proton transfer from the ribose O<sup>3'</sup>H<sup>3' </sup>group in ATP to Asp440 via a shuttling water molecule and P<sup>A</sup>-O<sup>3A</sup> bond cleavage and O<sup>3'</sup>-P<sup>A</sup> bond formation. The energy profile of this route is consistent with the observed reaction kinetics. In a higher energy ES conformation, Mg<sub>A</sub><sup>2+</sup> is bound to the O<sub>δ1</sub>(Asp440) atom as suggested in the relevant crystal structure of the protein with a substrate analog. The computed energy profile initiated by this ES is characterized by higher energy expenses to complete the reaction. Consistently with experimental data, we show that the Asp440Ala mutant of the enzyme should exhibit a reduced but retained activity. All considered reaction pathways include proton wires from the O<sup>3'</sup>H<sup>3' </sup>group via shuttling water molecules. </p>

scholarly journals Computational study on the mechanism of metal-free photochemical borylation of aryl halides

2021 ◽  
Author(s):  
Chenhao Tu ◽  
Nana Ma ◽  
Qingli Xu ◽  
Wenyue Guo ◽  
Lanxin Zhou ◽  
...  
Keyword(s):  
Density Functional ◽  
Uv Light ◽  
Computational Study ◽  
Halogen Bond ◽  
Bond Cleavage ◽  
Aryl Halides ◽  
Homolytic Cleavage ◽  
Functional Theory ◽  
Aryl Radicals

C-radical borylation is an significant approach for the construction of carbon−boron bond. Photochemical borylation of aryl halides successfully applied this strategy. However, precise mechanisms, such as the generation of aryl radicals and the role of base additive(TMDAM) and water, remain controversy in these reactions. In this study, photochemical borylation of aryl halides has been researched by density functional theory (DFT) calculations. Indeed, the homolytic cleavage of the C−X bond under irradiation with UV-light is a key step for generation of aryl radicals. Nevertheless, the generation of aryl radicals may also undergo the process of single electron transfer and the heterolytic carbon-halogen bond cleavage sequence, and the latter is favorable during the reaction.

Acylation du (cyclopropylméthyl)triméthylsilane. Une nouvelle voie d'accès aux énones non conjuguées

1981 ◽  
Vol 59 (5) ◽  
pp. 802-806 ◽  
Author(s):  
M. Grignon-Dubois ◽  
J. Dunoguès ◽  
R. Calas
Keyword(s):  
Saturated Hydrocarbon ◽  
Chloroacetyl Chloride ◽  
Competitive Reaction ◽  
Acyl Chlorides ◽  
Unsaturated Ketones ◽  
Unsaturated Acyl ◽  
Catalytic Role ◽  
Convenient Route ◽  
Allylic Cleavage

Acylation of (cyclopropylmethyl)trimethylsilane using RCOCl/AlCl3 (R: saturated hydrocarbon group) constitutes a mild, convenient route to β,γ-unsaturated ketones free from the conjugated isomers. With α,β-unsaturated acyl chlorides a competitive reaction between the C—H and C—Si allylic cleavage is observed whereas chloroacetyl chloride affords the γ,δ-ethylenic corresponding ketone. A mechanism involving the catalytic role of HCl in the formation of β,γ-unsaturated and chloroketones is proposed.

scholarly journals Diversification of function in the haloacid dehalogenase enzyme superfamily: The role of the cap domain in hydrolytic phosphoruscarbon bond cleavage

2006 ◽  
Vol 34 (6) ◽  
pp. 394-409 ◽  
Author(s):  
Sushmita D. Lahiri ◽  
Guofeng Zhang ◽  
Debra Dunaway-Mariano ◽  
Karen N. Allen
Keyword(s):  
Bond Cleavage ◽  
Haloacid Dehalogenase ◽  
Enzyme Superfamily
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