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...
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.
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...
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.
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