The non-catalyzed and Lewis acid (LA) catalyzed Diels-Alder (DA) reaction between R-(-)-carvone 1... more The non-catalyzed and Lewis acid (LA) catalyzed Diels-Alder (DA) reaction between R-(-)-carvone 1R and isoprene 2 has been studied within Molecular Electronic Density Theory (MEDT) by using DFT calculations at the B3LYP/6-311 + + G(d,p) computational level. Analysis of the theoretical reactivity indices at the ground state of the reagents indicates that carvone 1R plays the role of an electrophile whereas isoprene 2 should be regarded as nucleophile participating in a polar process. The presence of the LA catalyst signi cantly increases the electrophilicity ω of carvone 1R, resulting in improved reactivity and selectivities in the LA catalyzed DA reaction. The presence of the LA catalyst signi cantly reduces the activation Gibbs free energy by increasing the polarity of the DA reaction. The computed relative Gibbs free energies clearly demonstrate a high degree of region-and stereoselectivity in this LA catalyzed DA reaction, which is consistent with the experimental ndings. Through an examination of the Electron Localization Function (ELF), it became evident that the LA catalyzed DA reaction follows a non-concerted two-stage one-step mechanism. Finally, docking analysis was conducted for cycloadducts and 4, docked them to the main protease of HIV-1 (5W4Q and 1A8O), and their binding was compared to the antiviral drug Azidothymidine (AZT). The results indicated that cycloadduct exhibited lower binding energies than AZT, suggesting a signi cant potential for anti-HIV activity.
The [3+2] cycloaddition (32CA) reaction between nitrone and an electronic deficient methyl acetyl... more The [3+2] cycloaddition (32CA) reaction between nitrone and an electronic deficient methyl acetylene carboxylate (MAC) was studied within the Molecular Electron Density Theory (MEDT) by using DFT functional combined with B3LYP and 6-31+(d,p) as a basis set. Conceptual DFT (CDFT) analysis allows to characterize nitrone and MAC as a strong nucleophile and a strong electrophile respectively, while analysis of the Parr functions allows explaining the chemo-and regioselectivity observed experimentally in complete agreement with the barrier activation. Electron localization function (ELF) topological analysis of several points along intrinsic reaction coordinate (IRC) profile associated with the energetically most favorable reaction channel permits to establish a non-concerted twostage one-step molecular mechanism. The reaction begins by the creation of a pseudoradical center at the terminal carbon, firstly at the methyl acetylene carboxylate derivative (MAC), and secondly at the nitrone framework which immediately promotes the formation of the first O-C single bond by donation of some electron density of oxygen atom lone pairs.
In this study, we were interested in the physic-chemical characterization (SEM, BET, X-ray, DTA-T... more In this study, we were interested in the physic-chemical characterization (SEM, BET, X-ray, DTA-TG, and IR) of the flying ashes stemming of the combustion of the coal in the thermal power station of JORF-LASFAR in EL Jadida (Morocco). On the one hand, we deduce from this study that these flying ashes are belonging to the class F Fly ash (according to ASTM standards). The X-ray diffraction shows that the ashes are mainly constituted by the aluminosilicate and the quartz. The thermal analysis (DTA-TG), the IR, and SEM proves the presence of the carbonates of the calcium. On the other hand, after washing the ashes, with the distilled water, an equilibrium of adsorption-desorption of the carbonates was reached after 30 minutes.
According to World Health Organization norms, the upper limit of fluoride concentration in drinki... more According to World Health Organization norms, the upper limit of fluoride concentration in drinking water was I .5 mg 1-l. The purpose of this study is to apply a hybrid process that combines the adsorption on conventional solid adsorbents such as aluminum and zirconium oxide along with a specific Donnan dialysis (DD) procedure to treat groundwater with an excessive fluoride concentration of 4 mg 1-l resulting from phosphate mining in Morocco. The DD pre-industrial pilot was equipped with ACS anion-exchange membranes (Tokuyama Co.) having a total area of 0.176 m2. The DD process was studied under two circulating modes of the receiver solution, single pass and batch, whereas the feed solution flowed continuously as a single pass. To maintain the fluoride concentration below the acceptable values at the outlet of the feed compartment, the extracted fluoride ions are adsorbed by Al,O, and ZrO,, which were added in the receiver solution. The mineralization of the treated groundwater was not modified. The cation composition remained unchanged, whereas anions, except chloride, were partially eliminated and substituted by chloride ions, giving a fluoride concentration below the acceptable values.
Cahiers de l'Association Scientifique Européenne pour l'Eau et la Santé, 2000
• Contamination des eaux souterraines et des sols par les fluorures et leur impact à proximité de... more • Contamination des eaux souterraines et des sols par les fluorures et leur impact à proximité des mines et d'usines d'exploitation des phosphates (Maroc) • mination of groundwater and soils. This study revealed that the soil and groundwater collected from somes sites of the fluorosis aera contained high level of ftuoride. Statistical analysis of the data showed a good corrélation between concentration of the ftuoride and the fluorosis dental in this région.
In this study, we propose a new approach that their purposes to facilitate the theoretical examin... more In this study, we propose a new approach that their purposes to facilitate the theoretical examinations of the intramolecular Diels-Alder (IMDA) reactions of triene amide and other IMDA reactions. In this end, the nature of reaction mechanism (NRM) will be determined by evaluating the contribution of binding chain on the HOMO and LUMO energies of triene amide. During our study, we have used the density functional theory (DFT) combined with B3LYP hybrid and 6-31G(d,p) basis set level. The results found shows that the binding chain has a negligible contribution on the HOMO and LUMO energies of triene amide molecule. Therefore, the diene and dienophile are treated as they were in isolated fragments. Thus the calculation of the NRM reveals that these reactions are at normal electronic demand (NED) in accordance with the results found by charge transfer between fragments in the transition state.
In this study, we will be studied quantitatively the binding chain role and understanding the int... more In this study, we will be studied quantitatively the binding chain role and understanding the interactions between diene (D) and dienophile (Dp) fragments in the intra-molecule (IM) and identifying the physicochemical variations of these fragments when passing from the isolated fragment (IF) to the linked fragment (LF) at the intra-molecule using the nucleophilic and electrophilic Fukui functions calculated by DFT (density functional theory) method with the B3LYP hybrid and 6-31G(d,p) basis set level. The results found show that the binding chain has a low contribution to the physicochemical character of the intra-molecule and that his principal role focuses on the transfer of the charge between fragments, the quantitative studies we permit to conclude that the nucleophilic Fukui functions of Diene are remains unchanged in the linked fragment than that in diene (D) of isolated fragment (FDIF) as (and the electrophilic Fukui function of dienophile is divided almost in half in the lin...
In this study, we propose a new approach that their purposes to facilitate the theoretical examin... more In this study, we propose a new approach that their purposes to facilitate the theoretical examinations of the intramolecular Diels-Alder (IMDA) reactions of triene amide and other IMDA reactions. In this end, the nature of reaction mechanism (NRM) will be determined by evaluating the contribution of binding chain on the HOMO and LUMO energies of triene amide. During our study, we have used the density functional theory (DFT) combined with B3LYP hybrid and 6-31G(d,p) basis set level. The results found shows that the binding chain has a negligible contribution on the HOMO and LUMO energies of triene amide molecule. Therefore, the diene and dienophile are treated as they were in isolated fragments. Thus the calculation of the NRM reveals that these reactions are at normal electronic demand (NED) in accordance with the results found by charge transfer between fragments in the transition state.
1Team of chemoinformatics research and spectroscopy and quantum chemistry, Department of chemistr... more 1Team of chemoinformatics research and spectroscopy and quantum chemistry, Department of chemistry, physical and chemistry lab,
In this study, we proposed to examine the reactivity of the intramolecular cycloaddition Diels-Al... more In this study, we proposed to examine the reactivity of the intramolecular cycloaddition Diels-Alder (IMDA) reaction of the molecule triene amide by chemical descriptors established globally in the intermolecular reactions (DA), such as of electrophilic index ω and the nucleophilic index N. In order to provide the power releasing or withdrawing of electrons of the diene (D) and dienophile (Dp) fragments in the intramolecular molecule, the polarity of the reaction can be evaluated by the application of these two factors, applied locally to the diene (D) and dienophile (Dp) fragments, other parameters have been introduced to enrich these results, such as transferability index γ and charge transfer (CT) in a transition state. During our study we used density functional theory (DFT) in the hybrid B3LYP and basis set level 6-31G (d, p), the geometries are optimized for the reactants, transition states as well for products, the calculation of the charge transfer is carried out using the n...
journal of chemistry and chemical engineering, 2017
In this paper, we have study the binding chain role and the physicochemical variations between di... more In this paper, we have study the binding chain role and the physicochemical variations between diene and dienophile fragments through the linked (intra-molecule) and isolated fragments in order to facilitate and better understanding the intramolecular cycloaddition Diels-Alder reaction mechanism, and was evaluated by using the nucleophilicity and electrophilicity indices calculated by DFT method in conjunction with B3LYP hybrid and 6-31G(d,p) basis set level. The results found elucidate that the binding chain (CH2)n (n=2 to 3) has a negligible contribution to the physicochemical character of the fragments and that his principal role is the perturbation between fragments (µ diene ≠µ dienophile ) in the intra-molecule. Therefore, the qualitative studies we permit to conclude that the diene and dienophile fragments are fully preserved their characters in the linked fragment (intra-molecule) compared than that in the isolated fragment (IF) as well the nucleophilicity index is N diene(IF...
The regioselectivity in the intramolecular Diels Alder reaction (IMDA) of the molecule triene-ami... more The regioselectivity in the intramolecular Diels Alder reaction (IMDA) of the molecule triene-amide for the synthesis in the hexahydroindole product, is done the object of our present work, two product regioisomers are feasible, the analysis of PES (potential energy surface) shows that the fused isomer is the main product and that bridged isomer is the minority product, this preference is also confirmed by the maximum hardness global (MHP), in this study we used the density functional theory (DFT) at the hybrid B3LYP and basis set level 6-31G (d, p), the geometries are optimized for reagents, thus the transition states and for products, the calculation of the bond order (BO) using natural population analysis (NBO) explains that all the transition states are asynchronous, and the analysis by IRC (intrinsic reaction coordinate) of the majority compound shows that the reaction IMDA is concerted. The effect of the solvent toluene is taken into account by using the polarizable contium m...
Isotropic 1 H and 13 C nuclear magnetic shielding constants of hexahydroindoles products of intra... more Isotropic 1 H and 13 C nuclear magnetic shielding constants of hexahydroindoles products of intramolecular Diels-Alder of the triene-amide reaction have been calculated by employing the gauge-including-atomic-orbital (GIAO), Continuous Set of Gauge Transformations (CSGT) and a slight variation on the CSGT (IGAIM) methods at the B3LYP/6-311(d,p) density functional level of theory. Geometry of each compound has been optimized employing 6-31G(d,p) basis sets. The comparison of the theoretical results to the experimental results of the Ha compound shows that the GIAO method is the most reliable. On the other hand we calculate the chemicals shifts of the carbon ( 13 C) and hydrogen ( 1 H) of the Hb and Hc compounds. This calculation was performed using the B3LYP functional, using the GIAO method at the level of the following bases: 6-31G, 6-31 G(d), 6-31G(d,p), 6-311G, 6-311G(d). The theoretical trends are compared with experimental data taken from the literature. The least squares regre...
We are interested in studying the phosphorylation of the kinase activation loop, distinguishing t... more We are interested in studying the phosphorylation of the kinase activation loop, distinguishing the passage from the unphosphorylated to the phosphorylated form without allostery. We performed an interaction study to trace the change of interactions between the activation segment and the kinase catalytic core, before and after phosphorylation. Results show that the structural changes are mainly due to the attraction between the phosphate group and guanidine groups of the arginine side chains of RD-pocket, which are constituted mainly of guanidine groups of the catalytic loop, the β9, and the αC helix. This attraction causes propagation of structural variation of the activation segment, principally towards the N-terminal. The structural variations are not made on all the amino acids of the activation segment; they are conditioned by the existence of two beta sheets stabilizing the loop during phosphorylation. The first, β6-β9 sheet is usually present in most of the kinases; the second, β10-β11 is formed due to the interaction between the main chain amino acids of the activation loop and the αEF/αF loop.
The mechanistic nature of a [3+2] cycloaddition reaction involving zwitterionic species has been ... more The mechanistic nature of a [3+2] cycloaddition reaction involving zwitterionic species has been investigated, and the changes of electron density related to the O–C and C–C bond formation along the intrinsic reaction coordinate have been characterized. This polar [3+2] cycloaddition reaction, which takes place through a non-concerted two-stage one-step mechanism, proceeds with a moderate Gibbs free activation energy of 21 kcal mol−1. The reaction begins by the creation of a pseudoradical centre at the central carbon, first on the dimethyl acetylenedicarboxylate, and second on the nitrone framework. This immediately favours the formation of the first O–C single bond by donation of some electron density of the oxygen atom lone pairs, which represents the most attractive centre in this cycloaddition reaction.
The notion of aromaticity is an elusive concept, typically delineated as an electron delocalizati... more The notion of aromaticity is an elusive concept, typically delineated as an electron delocalization pattern within a cyclic structure, and is characterized by unusual stability, reactivity, and other properties. Recently, the aromatic concept has been extended to inorganic molecules and saturated systems. In our work, the so-called pericyclic transition state structures (TSs) involved in aza-Diels-Alder reactions are investigated. Interestingly, geometries and energy barriers evidence that these reactions are highly energetic and are extremely asynchronous. Additionally the localized orbital locator, ELF and QTAIM topological analyses have proven that at least one pair of atoms is not bound at the TS configuration. Moreover, HOMA and PDI indexes show that these TSs where aromaticity is not important. Therefore, these results provoke us to rule out the aromatic character of these so-called pericyclic TSs structures.
A defined theoretical study was performed, the mainly factors controlling the preparation of 3-fl... more A defined theoretical study was performed, the mainly factors controlling the preparation of 3-fluoroalkylated 1,4,2-oxathiazoles were completely investigated, to this end, the B3LYP/6-31G(d) computational level within the Molecular Electron Density Theory was employed. A significant predominance of 3-fluoroalkylated 1,4,2-oxathiazoles derivatives (D1) has been generated via [3 + 2] cycloaddition between thioketone and nitrile oxide, rationalized by the electrophilic P + and nucleophilic P Parr functions at the reactive sites of reagents, affording the S 1-C 3 regioselectivity observed experimentally. Besides, an investigation of the relative energies of reaction, Gibbs free energy and barrier activation profile clearly evidences that experimentally isolated D1 is the most reachable product of this reaction, both kinetically and thermodynamically. Importantly, the high polarization of C=S bond toward S sulfur atom over O-C bond polarization make it the nitrile oxide more electrophile instead nucleophile. Furthermore, the ELF topological patterns of the most favorable product indicate that the formation of new bonds in the 32CA reaction between thioketone and nitrile oxide will appear through two unrelated manners, the first is formed by coupling of S-to-C pseudoradical center generated at the most significant atom, while the second is formed by sharing nitrogen non-bonding electron-density and a carbon pseudoradical center via a non-concerted two-stage one-step molecular mechanism.
The non-catalyzed and Lewis acid (LA) catalyzed Diels-Alder (DA) reaction between R-(-)-carvone 1... more The non-catalyzed and Lewis acid (LA) catalyzed Diels-Alder (DA) reaction between R-(-)-carvone 1R and isoprene 2 has been studied within Molecular Electronic Density Theory (MEDT) by using DFT calculations at the B3LYP/6-311 + + G(d,p) computational level. Analysis of the theoretical reactivity indices at the ground state of the reagents indicates that carvone 1R plays the role of an electrophile whereas isoprene 2 should be regarded as nucleophile participating in a polar process. The presence of the LA catalyst signi cantly increases the electrophilicity ω of carvone 1R, resulting in improved reactivity and selectivities in the LA catalyzed DA reaction. The presence of the LA catalyst signi cantly reduces the activation Gibbs free energy by increasing the polarity of the DA reaction. The computed relative Gibbs free energies clearly demonstrate a high degree of region-and stereoselectivity in this LA catalyzed DA reaction, which is consistent with the experimental ndings. Through an examination of the Electron Localization Function (ELF), it became evident that the LA catalyzed DA reaction follows a non-concerted two-stage one-step mechanism. Finally, docking analysis was conducted for cycloadducts and 4, docked them to the main protease of HIV-1 (5W4Q and 1A8O), and their binding was compared to the antiviral drug Azidothymidine (AZT). The results indicated that cycloadduct exhibited lower binding energies than AZT, suggesting a signi cant potential for anti-HIV activity.
The [3+2] cycloaddition (32CA) reaction between nitrone and an electronic deficient methyl acetyl... more The [3+2] cycloaddition (32CA) reaction between nitrone and an electronic deficient methyl acetylene carboxylate (MAC) was studied within the Molecular Electron Density Theory (MEDT) by using DFT functional combined with B3LYP and 6-31+(d,p) as a basis set. Conceptual DFT (CDFT) analysis allows to characterize nitrone and MAC as a strong nucleophile and a strong electrophile respectively, while analysis of the Parr functions allows explaining the chemo-and regioselectivity observed experimentally in complete agreement with the barrier activation. Electron localization function (ELF) topological analysis of several points along intrinsic reaction coordinate (IRC) profile associated with the energetically most favorable reaction channel permits to establish a non-concerted twostage one-step molecular mechanism. The reaction begins by the creation of a pseudoradical center at the terminal carbon, firstly at the methyl acetylene carboxylate derivative (MAC), and secondly at the nitrone framework which immediately promotes the formation of the first O-C single bond by donation of some electron density of oxygen atom lone pairs.
In this study, we were interested in the physic-chemical characterization (SEM, BET, X-ray, DTA-T... more In this study, we were interested in the physic-chemical characterization (SEM, BET, X-ray, DTA-TG, and IR) of the flying ashes stemming of the combustion of the coal in the thermal power station of JORF-LASFAR in EL Jadida (Morocco). On the one hand, we deduce from this study that these flying ashes are belonging to the class F Fly ash (according to ASTM standards). The X-ray diffraction shows that the ashes are mainly constituted by the aluminosilicate and the quartz. The thermal analysis (DTA-TG), the IR, and SEM proves the presence of the carbonates of the calcium. On the other hand, after washing the ashes, with the distilled water, an equilibrium of adsorption-desorption of the carbonates was reached after 30 minutes.
According to World Health Organization norms, the upper limit of fluoride concentration in drinki... more According to World Health Organization norms, the upper limit of fluoride concentration in drinking water was I .5 mg 1-l. The purpose of this study is to apply a hybrid process that combines the adsorption on conventional solid adsorbents such as aluminum and zirconium oxide along with a specific Donnan dialysis (DD) procedure to treat groundwater with an excessive fluoride concentration of 4 mg 1-l resulting from phosphate mining in Morocco. The DD pre-industrial pilot was equipped with ACS anion-exchange membranes (Tokuyama Co.) having a total area of 0.176 m2. The DD process was studied under two circulating modes of the receiver solution, single pass and batch, whereas the feed solution flowed continuously as a single pass. To maintain the fluoride concentration below the acceptable values at the outlet of the feed compartment, the extracted fluoride ions are adsorbed by Al,O, and ZrO,, which were added in the receiver solution. The mineralization of the treated groundwater was not modified. The cation composition remained unchanged, whereas anions, except chloride, were partially eliminated and substituted by chloride ions, giving a fluoride concentration below the acceptable values.
Cahiers de l'Association Scientifique Européenne pour l'Eau et la Santé, 2000
• Contamination des eaux souterraines et des sols par les fluorures et leur impact à proximité de... more • Contamination des eaux souterraines et des sols par les fluorures et leur impact à proximité des mines et d'usines d'exploitation des phosphates (Maroc) • mination of groundwater and soils. This study revealed that the soil and groundwater collected from somes sites of the fluorosis aera contained high level of ftuoride. Statistical analysis of the data showed a good corrélation between concentration of the ftuoride and the fluorosis dental in this région.
In this study, we propose a new approach that their purposes to facilitate the theoretical examin... more In this study, we propose a new approach that their purposes to facilitate the theoretical examinations of the intramolecular Diels-Alder (IMDA) reactions of triene amide and other IMDA reactions. In this end, the nature of reaction mechanism (NRM) will be determined by evaluating the contribution of binding chain on the HOMO and LUMO energies of triene amide. During our study, we have used the density functional theory (DFT) combined with B3LYP hybrid and 6-31G(d,p) basis set level. The results found shows that the binding chain has a negligible contribution on the HOMO and LUMO energies of triene amide molecule. Therefore, the diene and dienophile are treated as they were in isolated fragments. Thus the calculation of the NRM reveals that these reactions are at normal electronic demand (NED) in accordance with the results found by charge transfer between fragments in the transition state.
In this study, we will be studied quantitatively the binding chain role and understanding the int... more In this study, we will be studied quantitatively the binding chain role and understanding the interactions between diene (D) and dienophile (Dp) fragments in the intra-molecule (IM) and identifying the physicochemical variations of these fragments when passing from the isolated fragment (IF) to the linked fragment (LF) at the intra-molecule using the nucleophilic and electrophilic Fukui functions calculated by DFT (density functional theory) method with the B3LYP hybrid and 6-31G(d,p) basis set level. The results found show that the binding chain has a low contribution to the physicochemical character of the intra-molecule and that his principal role focuses on the transfer of the charge between fragments, the quantitative studies we permit to conclude that the nucleophilic Fukui functions of Diene are remains unchanged in the linked fragment than that in diene (D) of isolated fragment (FDIF) as (and the electrophilic Fukui function of dienophile is divided almost in half in the lin...
In this study, we propose a new approach that their purposes to facilitate the theoretical examin... more In this study, we propose a new approach that their purposes to facilitate the theoretical examinations of the intramolecular Diels-Alder (IMDA) reactions of triene amide and other IMDA reactions. In this end, the nature of reaction mechanism (NRM) will be determined by evaluating the contribution of binding chain on the HOMO and LUMO energies of triene amide. During our study, we have used the density functional theory (DFT) combined with B3LYP hybrid and 6-31G(d,p) basis set level. The results found shows that the binding chain has a negligible contribution on the HOMO and LUMO energies of triene amide molecule. Therefore, the diene and dienophile are treated as they were in isolated fragments. Thus the calculation of the NRM reveals that these reactions are at normal electronic demand (NED) in accordance with the results found by charge transfer between fragments in the transition state.
1Team of chemoinformatics research and spectroscopy and quantum chemistry, Department of chemistr... more 1Team of chemoinformatics research and spectroscopy and quantum chemistry, Department of chemistry, physical and chemistry lab,
In this study, we proposed to examine the reactivity of the intramolecular cycloaddition Diels-Al... more In this study, we proposed to examine the reactivity of the intramolecular cycloaddition Diels-Alder (IMDA) reaction of the molecule triene amide by chemical descriptors established globally in the intermolecular reactions (DA), such as of electrophilic index ω and the nucleophilic index N. In order to provide the power releasing or withdrawing of electrons of the diene (D) and dienophile (Dp) fragments in the intramolecular molecule, the polarity of the reaction can be evaluated by the application of these two factors, applied locally to the diene (D) and dienophile (Dp) fragments, other parameters have been introduced to enrich these results, such as transferability index γ and charge transfer (CT) in a transition state. During our study we used density functional theory (DFT) in the hybrid B3LYP and basis set level 6-31G (d, p), the geometries are optimized for the reactants, transition states as well for products, the calculation of the charge transfer is carried out using the n...
journal of chemistry and chemical engineering, 2017
In this paper, we have study the binding chain role and the physicochemical variations between di... more In this paper, we have study the binding chain role and the physicochemical variations between diene and dienophile fragments through the linked (intra-molecule) and isolated fragments in order to facilitate and better understanding the intramolecular cycloaddition Diels-Alder reaction mechanism, and was evaluated by using the nucleophilicity and electrophilicity indices calculated by DFT method in conjunction with B3LYP hybrid and 6-31G(d,p) basis set level. The results found elucidate that the binding chain (CH2)n (n=2 to 3) has a negligible contribution to the physicochemical character of the fragments and that his principal role is the perturbation between fragments (µ diene ≠µ dienophile ) in the intra-molecule. Therefore, the qualitative studies we permit to conclude that the diene and dienophile fragments are fully preserved their characters in the linked fragment (intra-molecule) compared than that in the isolated fragment (IF) as well the nucleophilicity index is N diene(IF...
The regioselectivity in the intramolecular Diels Alder reaction (IMDA) of the molecule triene-ami... more The regioselectivity in the intramolecular Diels Alder reaction (IMDA) of the molecule triene-amide for the synthesis in the hexahydroindole product, is done the object of our present work, two product regioisomers are feasible, the analysis of PES (potential energy surface) shows that the fused isomer is the main product and that bridged isomer is the minority product, this preference is also confirmed by the maximum hardness global (MHP), in this study we used the density functional theory (DFT) at the hybrid B3LYP and basis set level 6-31G (d, p), the geometries are optimized for reagents, thus the transition states and for products, the calculation of the bond order (BO) using natural population analysis (NBO) explains that all the transition states are asynchronous, and the analysis by IRC (intrinsic reaction coordinate) of the majority compound shows that the reaction IMDA is concerted. The effect of the solvent toluene is taken into account by using the polarizable contium m...
Isotropic 1 H and 13 C nuclear magnetic shielding constants of hexahydroindoles products of intra... more Isotropic 1 H and 13 C nuclear magnetic shielding constants of hexahydroindoles products of intramolecular Diels-Alder of the triene-amide reaction have been calculated by employing the gauge-including-atomic-orbital (GIAO), Continuous Set of Gauge Transformations (CSGT) and a slight variation on the CSGT (IGAIM) methods at the B3LYP/6-311(d,p) density functional level of theory. Geometry of each compound has been optimized employing 6-31G(d,p) basis sets. The comparison of the theoretical results to the experimental results of the Ha compound shows that the GIAO method is the most reliable. On the other hand we calculate the chemicals shifts of the carbon ( 13 C) and hydrogen ( 1 H) of the Hb and Hc compounds. This calculation was performed using the B3LYP functional, using the GIAO method at the level of the following bases: 6-31G, 6-31 G(d), 6-31G(d,p), 6-311G, 6-311G(d). The theoretical trends are compared with experimental data taken from the literature. The least squares regre...
We are interested in studying the phosphorylation of the kinase activation loop, distinguishing t... more We are interested in studying the phosphorylation of the kinase activation loop, distinguishing the passage from the unphosphorylated to the phosphorylated form without allostery. We performed an interaction study to trace the change of interactions between the activation segment and the kinase catalytic core, before and after phosphorylation. Results show that the structural changes are mainly due to the attraction between the phosphate group and guanidine groups of the arginine side chains of RD-pocket, which are constituted mainly of guanidine groups of the catalytic loop, the β9, and the αC helix. This attraction causes propagation of structural variation of the activation segment, principally towards the N-terminal. The structural variations are not made on all the amino acids of the activation segment; they are conditioned by the existence of two beta sheets stabilizing the loop during phosphorylation. The first, β6-β9 sheet is usually present in most of the kinases; the second, β10-β11 is formed due to the interaction between the main chain amino acids of the activation loop and the αEF/αF loop.
The mechanistic nature of a [3+2] cycloaddition reaction involving zwitterionic species has been ... more The mechanistic nature of a [3+2] cycloaddition reaction involving zwitterionic species has been investigated, and the changes of electron density related to the O–C and C–C bond formation along the intrinsic reaction coordinate have been characterized. This polar [3+2] cycloaddition reaction, which takes place through a non-concerted two-stage one-step mechanism, proceeds with a moderate Gibbs free activation energy of 21 kcal mol−1. The reaction begins by the creation of a pseudoradical centre at the central carbon, first on the dimethyl acetylenedicarboxylate, and second on the nitrone framework. This immediately favours the formation of the first O–C single bond by donation of some electron density of the oxygen atom lone pairs, which represents the most attractive centre in this cycloaddition reaction.
The notion of aromaticity is an elusive concept, typically delineated as an electron delocalizati... more The notion of aromaticity is an elusive concept, typically delineated as an electron delocalization pattern within a cyclic structure, and is characterized by unusual stability, reactivity, and other properties. Recently, the aromatic concept has been extended to inorganic molecules and saturated systems. In our work, the so-called pericyclic transition state structures (TSs) involved in aza-Diels-Alder reactions are investigated. Interestingly, geometries and energy barriers evidence that these reactions are highly energetic and are extremely asynchronous. Additionally the localized orbital locator, ELF and QTAIM topological analyses have proven that at least one pair of atoms is not bound at the TS configuration. Moreover, HOMA and PDI indexes show that these TSs where aromaticity is not important. Therefore, these results provoke us to rule out the aromatic character of these so-called pericyclic TSs structures.
A defined theoretical study was performed, the mainly factors controlling the preparation of 3-fl... more A defined theoretical study was performed, the mainly factors controlling the preparation of 3-fluoroalkylated 1,4,2-oxathiazoles were completely investigated, to this end, the B3LYP/6-31G(d) computational level within the Molecular Electron Density Theory was employed. A significant predominance of 3-fluoroalkylated 1,4,2-oxathiazoles derivatives (D1) has been generated via [3 + 2] cycloaddition between thioketone and nitrile oxide, rationalized by the electrophilic P + and nucleophilic P Parr functions at the reactive sites of reagents, affording the S 1-C 3 regioselectivity observed experimentally. Besides, an investigation of the relative energies of reaction, Gibbs free energy and barrier activation profile clearly evidences that experimentally isolated D1 is the most reachable product of this reaction, both kinetically and thermodynamically. Importantly, the high polarization of C=S bond toward S sulfur atom over O-C bond polarization make it the nitrile oxide more electrophile instead nucleophile. Furthermore, the ELF topological patterns of the most favorable product indicate that the formation of new bonds in the 32CA reaction between thioketone and nitrile oxide will appear through two unrelated manners, the first is formed by coupling of S-to-C pseudoradical center generated at the most significant atom, while the second is formed by sharing nitrogen non-bonding electron-density and a carbon pseudoradical center via a non-concerted two-stage one-step molecular mechanism.
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