Mechanistic investigation on N → Cα → O relay via non-Brook rearrangement: reaction conditions promote synthesis of furo[3,2-c]pyridinones

2017 ◽  
Vol 15 (43) ◽  
pp. 9127-9138 ◽  
Author(s):  
Lihan Zhu ◽  
Haiyan Yuan ◽  
Jingping Zhang
Keyword(s):  
Dft Calculations ◽  
Reaction Conditions ◽  
Mechanistic Investigation ◽  
Brook Rearrangement ◽  
Rearrangement Reaction

DFT calculations disclosed the effect of reaction conditions on the effective anion relay sequence of a NaH promoted non-Brook rearrangement.

DFT Study and Synthesis of Novel Bioactive Bispyrazole Using Mg/AlLDH as a Solid Base Catalyst

2020 ◽  
Vol 14 ◽  
Author(s):  
Soufiane Akhramez ◽  
Youness Achour ◽  
Mustapha Diba ◽  
Lahoucine Bahsis ◽  
Hajiba Ouchetto ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Experimental Finding ◽  
Biological Activities ◽  
Condensation Reaction ◽  
Aromatic Aldehydes ◽  
Mechanistic Study ◽  
Knoevenagel Reaction ◽  
Solid Base ◽  
Reaction Conditions ◽  
Aryl Aldehyde

Background: In this study, an efficient synthesis of novel bispyrazole heterocyclic molecules by condensation of substituted aromatic aldehydes with 1,3-diketo-N-phenylpyrazole by using Mg/Al-LDH as heterogeneous catalyst is reported. The attractive features of this protocol are as follows: mild reaction conditions, good yields and easiness of the catalyst separation from the reaction mixture. Further, a mechanistic study has been performed by using DFT calculations to explain the observed selectivity of the condensation reaction between aryl aldehyde and 1,3-diketo-N-phenylpyrazole via Knoevenagel reaction. The local electrophilicity/ nucleophilicity that allows explaining correctly the experimental finding. Methods: The bispyrazole derivatives 3a-m were prepared by condensation reaction of substituted aromatic aldehydes with 1,3-diketo-Nphenylpyrazole by using Mg/Al-LDH as heterogeneous catalyst under THF solvent at the refluxing temperature. Objective: To synthesize a novel bispyrazole heterocyclic molecule may be have important biological activities and thus can be good candidates for pharmaceutical applications. Results: This protocol describes the Synthesis of Bioactive Compounds under mild reaction conditions, good yields and easiness of the catalyst separation from the reaction mixture. Further, a mechanistic study has been performed by using DFT calculations to explain the observed selectivity of the condensation reaction between aryl aldehyde and 1,3-diketo-N-phenylpyrazole via Knoevenagel reaction. The local electrophilicity/ nucleophilicity that allows explaining correctly the experimental finding. Conclusion: In summary, the pharmacologically interesting bis-pyrazole derivatives have been synthesized through Mg/Al-LDH as a solid base catalyst, in THF as solvent. Thus, the synthesized bioactive compounds containing the pyrazole ring may be have important biological activities and thus can be good candidates for pharmaceutical applications. Therefore, the catalyst Mg/Al-LDH showed high catalytic activity. Besides, a series of bispyrazole molecules were synthesized with a good yield and easy separation of the catalyst by simple filtration. Moreover, DFT calculations and reactivity indexes are used to explain the selectivity of the condensation reaction between aryl benzaldehyde and 1,3-diketo-Nphenylpyrazole via Knoevenagel reaction, and the results are in good agreement with the experimental finding.

scholarly journals Mechanistic investigation into phenol oxidation by IBX elucidated by DFT calculations

2020 ◽  
Vol 18 (6) ◽  
pp. 1117-1129 ◽  
Author(s):  
Amritpal Kaur ◽  
Alireza Ariafard
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Density Functional ◽  
Phenol Oxidation ◽  
Hypervalent Iodine ◽  
Functional Theory ◽  
Mechanistic Investigation ◽  
Oxidation Of Phenols ◽  
Double Oxidation

Density functional theory (DFT) at the SMD/M06-2X/def2-TZVP//SMD/M06-2X/LANL2DZ(d),6-31G(d) level was used to explore the regioselective double oxidation of phenols by a hypervalent iodine(v) reagent (IBX) to give o-quinones.

scholarly journals DBU Catalyzed Phospho-Aldol-Brook Rearrangement for Rapid Preparation of α-Phosphates Amide in Solvent-Free Conditions

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1445
Author(s):  
Shunhong Chen ◽  
Shengxin Guo ◽  
Feng He ◽  
Yingxia Zhang ◽  
Zengxue Wu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Solvent Free ◽  
The Novel ◽  
Rapid Preparation ◽  
Good Tolerance ◽  
Amide Derivatives ◽  
Solvent Free Conditions ◽  
Brook Rearrangement ◽  
Rearrangement Reaction ◽  
Dialkyl Phosphites

The 1,8-diazabicyclo [5.4.0] undec-7-ene DBU-catalyzed Phospho-Aldol-Brook Rearrangement reaction of α-ketoamide and dialkyl phosphites was developed under solvent-free at room temperature. The novel α-Phosphate Amide derivatives could be obtained with good yield (86–96%), which also exhibited good tolerance of various dialkyl phosphites and α-ketoamide, including isatins. In addition, the reaction was conducted in both gram-scale and mol-scale, and the title compounds could also be obtained in excellent yield (more than 91%) within 5 min.

scholarly journals Isoxazolium N-ylides and 1-oxa-5-azahexa-1,3,5-trienes on the way from isoxazoles to 2H-1,3-oxazines

2014 ◽  
Vol 10 ◽  
pp. 1896-1905 ◽  
Author(s):  
Alexander F Khlebnikov ◽  
Mikhail S Novikov ◽  
Yelizaveta G Gorbunova ◽  
Ekaterina E Galenko ◽  
Kirill I Mikhailov ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Experimental Studies ◽  
Diazo Compounds ◽  
Stationary Points ◽  
Reaction Intermediates ◽  
Reaction Conditions ◽  
Open Chain ◽  
Isoxazole Ring ◽  
Diazo Esters ◽  
Probable Reaction

Theoretical and experimental studies of the reaction of isoxazoles with diazo compounds show that the formation of 2H-1,3-oxazines proceeds via the formation of (3Z)-1-oxa-5-azahexa-1,3,5-trienes which undergo a 6π-cyclization. The stationary points corresponding to the probable reaction intermediates, isoxazolium N-ylides, were located by DFT calculations at the B3LYP/6-31G(d) level only for derivatives without a substituent in position 3 of the isoxazole ring. These isoxazolium N-ylides are thermodynamically and kinetically very unstable. According to the calculations and experimental results 2H-1,3-oxazines are usually more thermodynamically stable than the corresponding open-chain isomers, (3Z)-1-oxa-5-azahexa-1,3,5-trienes. The exception are oxaazahexatrienes derived from 5-alkoxyisoxazoles, which are thermodynamically more stable than the corresponding 2H-1,3-oxazines. Therefore, the reaction of diazo esters with 5-alkoxyisoxazoles is a good approach to 1,4-di(alkoxycarbonyl)-2-azabuta-1,3-dienes. The reaction conditions for the preparation of aryl- and halogen-substituted 2H-1,3-oxazines and 1,4-di(alkoxycarbonyl)-2-azabuta-1,3-dienes from isoxazoles were investigated.

scholarly journals Estimation of Bite Angle Effect on the Electronic Structure of Cobalt-Phosphine Complexes: A QTAIM Study

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Tamara Papp ◽  
László Kollár ◽  
Tamás Kégl
Keyword(s):  
Electronic Structure ◽  
Simple Model ◽  
Dft Calculations ◽  
Model Compound ◽  
Carbonyl Ligand ◽  
Reaction Conditions ◽  
Phosphine Complexes ◽  
Bite Angle ◽  
Angle Effect ◽  
Donor Character

The influence of bite angle in bisphosphine complexes has been modeled by DFT calculations employing the simple model compound HCo(CO)(PP) (PP = Xantphos or two monophosphine ligands). The increase of the bite angle increases the strength of the H–Co bond, whereas the C–O bond in the carbonyl ligand is weakened revealing an increase also in the donor character. The model compound cis-[HCo(CO)(PPh3)2] shows a flexibility both in terms of energy, and in terms of electronic structure upon the change of the P-Co-P angle, which can be a sign of the flexibility of PPh3 ligands in real reaction conditions.

scholarly journals Organic Base Catalyzed Cascade Phospho-Aldol-Brook Rearrangement Reaction of Isatins with H-phosphonates

2014 ◽  
Vol 34 (6) ◽  
pp. 1177 ◽  
Author(s):  
Wei Fang ◽  
Guogui Liu ◽  
Xiaofei Huang ◽  
Jun Jia ◽  
Xingwang Wang
Keyword(s):  
Organic Base ◽  
Brook Rearrangement ◽  
Rearrangement Reaction

scholarly journals Visible light induced alkene aminopyridylation using N-aminopyridinium salts as bifunctional reagents

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Yonghoon Moon ◽  
Bohyun Park ◽  
Inwon Kim ◽  
Gyumin Kang ◽  
Sanghoon Shin ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Electrostatic Interaction ◽  
Functional Group ◽  
Eosin Y ◽  
Pyridine Derivatives ◽  
Reaction Conditions ◽  
Radical Trapping ◽  
Molecular Complexity ◽  
Pyridinium Nitrogen ◽  
Mechanism Of The Reaction

Abstract The development of intermolecular alkene aminopyridylation has great potential for quickly increasing molecular complexity with two valuable groups. Here we report a strategy for the photocatalytic aminopyridylation of alkenes using a variety of N-aminopyridinium salts as both aminating and pyridylating reagents. Using Eosin Y as a photocatalyst, amino and pyridyl groups are simultaneously incorporated into alkenes, affording synthetically useful aminoethyl pyridine derivatives under mild reaction conditions. Remarkably, the C4-regioselectivity in radical trapping with N-aminopyridinium salt can be controlled by electrostatic interaction between the pyridinium nitrogen and sulfonyl group of β-amino radical. This transformation is characterized by a broad substrate scope, good functional group compatibility, and the utility of this transformation was further demonstrated by late-stage functionalization of complex biorelevant molecules. Combining experiments and DFT calculations on the mechanism of the reaction is investigated to propose a complete mechanism and regioselectivity.

scholarly journals Dinuclear thiolato-bridged arene ruthenium complexes: from reaction conditions and mechanism to synthesis of new complexes

RSC Advances ◽  
2020 ◽  
Vol 10 (66) ◽  
pp. 40106-40116
Author(s):  
Hedvika Primasová ◽  
Silviya Ninova ◽  
Mario de Capitani ◽  
Jana Daepp ◽  
Ulrich Aschauer ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Reaction Mechanisms ◽  
Ruthenium Complexes ◽  
Synthetic Route ◽  
Reaction Conditions

We used DFT calculations to understand the reaction mechanisms leading to the formation of dinuclear thiophenolato-bridged arene ruthenium complexes. DFT prompted us to modify the usual synthetic route, which enabled the synthesis of new complexes.

scholarly journals Pd-Catalyzed C–N Coupling Reactions Facilitated by Organic Bases: Mechanistic Investigation Leads to Enhanced Reactivity in the Arylation of Weakly Binding Amines

2019 ◽  
Author(s):  
Joseph Dennis ◽  
Nicholas White ◽  
Richard Liu ◽  
Stephen L. Buchwald
Keyword(s):  
Heterogeneous Reaction ◽  
Negative Influence ◽  
Catalytic Cycle ◽  
Coupling Reactions ◽  
Reaction Conditions ◽  
Organic Bases ◽  
Cross Coupling Reactions ◽  
Mechanistic Investigation ◽  
Relative Nucleophilicity ◽  
The Many

The ability to use soluble organic amine bases in Pd-catalyzed C–N cross-coupling reactions has provided a long-awaited solution to the many issues associated with employing traditional, heterogeneous reaction conditions. However, little is known about the precise function of these bases in the catalytic cycle and about the effect of variations in base structure on catalyst reactivity. We used <sup>19</sup>F NMR to analyze the kinetic behavior of C–N coupling reactions facilitated by different organic bases. In the case of aniline coupling reactions employing DBU, the resting state was a DBU-bound oxidative addition complex, LPd(DBU)(Ar)X, and the reaction was found to be inhibited by base. In general, however, depending on the binding properties of the chosen organic base, increased concentration of the base can have a positive or negative influence on the reaction rate. We propose a model in which the turnover-limiting step of the catalytic cycle depends on the relative nucleophilicity of the base compared to that of the amine. This hypothesis guided the discovery of new reaction conditions for the coupling of weakly binding amines, including secondary aryl amines, which were unreactive nucleophiles in our original protocol.

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