Evolution thermique de N-oxydes D'ω-dialkylamino alcanols-1

1984 ◽  
Vol 49 (10) ◽  
pp. 2410-2414 ◽  
Author(s):  
Didier Barbry ◽  
Bruno Hasiak
Keyword(s):  
Hydrogen Atom ◽  
Transition State ◽  
Tertiary Amine ◽  
Amino Alcohol ◽  
Cycloaddition Reaction ◽  
Reduction Process ◽  
The Other ◽  
Dipolar Cycloaddition ◽  
Oxidation Reduction ◽  
Planar Transition

The thermolysis of ω-dimethylamino-1-alkanol N-oxides affords ω-hydroxy-1-alkenes with dimethylhydroxylamine in good yields. The other basic products ( amino alcohol and isoxazolidine) involve oxidation-reduction process between the tertiary amine N-oxide and dimethylhydroxylamine, followed by 1,3-dipolar cycloaddition reaction. Pyrolysis of 5-piperidino-1-pentanol N-oxide proceeds on a path similar to the N-dimethyl compounds. The elimination of an hydrogen atom of the heterocycle does not occur: the preferred planar transition state cannot be attained because of the steric requirements of the ring.

Electrochemical Behavior of (Zn, Mn)-Al Nitrated Hydrotalcites

2012 ◽  
Vol 15 (4) ◽  
pp. 301-306 ◽  
Author(s):  
Alvaro Sampieri ◽  
Jorge Vázquez-Arenas ◽  
Ignacio González ◽  
Geolar Fetter ◽  
Heriberto Pfeiffer ◽  
...  
Keyword(s):  
Electrochemical Behavior ◽  
Lamellar Structure ◽  
Oxidation Process ◽  
Reduction Process ◽  
The Other ◽  
Oxidation Processes ◽  
Reduction Processes ◽  
Oxidation Reduction ◽  
Alkaline Conditions ◽  
Continuous Oxidation

The electrochemical behavior of synthetic binary, Zn-Al and Mn-Al, and ternary (Zn-Mn)-Al hydrotalcites (HT) was studied by cyclic voltammetry in alkaline conditions (pH≡12). The Zn-Al HT characterization revealed two irreversible and continuous oxidation processes: i) Zn0|Zn2+ and ii) Zn0|ZnO. On the other hand, the binary HT containing Mn presented a reversible behavior for the oxidation-reduction process Mn4+|Mn3+. The same oxidation-reduction processes were observed in the ternary HT. However, variations in the reduction-oxidation process were detected by XRD for the ternary HT as a result of spinel formation. These results could also be influenced due to a higher accessibility of manganese in HT since the morphology of hydrotalcite (lamellar structure) provides a regular distribution of Mn atoms interacting with Zn atoms through hydroxyl bridges.

Synthetic approaches towards bisspiro[naphthalene-2(1H),3′-(3H)pyrazol]-1-one-containing compounds

2006 ◽  
Vol 60 (3) ◽  
Author(s):  
A. Girgis ◽  
F. Osman ◽  
F. El-Samahy ◽  
I. Ahmed-Farag
Keyword(s):  
Cycloaddition Reaction ◽  
The Other ◽  
Dipolar Cycloaddition ◽  
Hydrazonoyl Chlorides ◽  
Other Hand ◽  
Synthetic Approaches

Abstract1,3-Dipolar cycloaddition reaction of bis{[4-(3,4-dihydro-(2H)-naphthalen-1-oxo-2-yl)methyl-idenephenyl]oxy}alkanes with nitrilimines (generated in situ by triethylamine dehydrohalogenation of the corresponding hydrazonoyl chlorides) in refluxing dry benzene afforded a mixture of monocycloadduct and dicycloadduct products in high regioselectivity. On the other hand, reaction of bis{[2-(3,4-dihydro-(2H)-naphthalen-1-oxo-2-yl)methylidenephenyl]oxy}alkanes with nitrilimines gave the corresponding dicycloadducts as the only isolable regioisomers.

scholarly journals Quantum chemistry study on the promoted reactivity of substituted cyclooctynes in bioorthogonal cycloaddition reactions

2021 ◽  
Vol 27 (1) ◽  
pp. 142-154
Author(s):  
Tayebeh Hosseinnejad ◽  
Marzieh Omrani-Pachin
Keyword(s):  
Activation Energy ◽  
Quantum Theory ◽  
Quantum Chemistry ◽  
Electron Density ◽  
Critical Points ◽  
Cycloaddition Reaction ◽  
Electronic Energy ◽  
The Other ◽  
Dipolar Cycloaddition ◽  
Topological Properties

Abstract In the present research, we focus on the energetics and electronic aspects of enhanced reactivity in the regioselective bioorthogonal 1,3-dipolar cycloaddition reaction of various substituted cyclooctynes with methyl azide, applying quantum chemistry approaches. In this respect, we assessed the structural and energetic properties of regioisomeric products and their corresponded transition states and calculated the reaction electronic energy changes and energy barriers through the cycloaddition pathways. The obtained results revealed that the trifluoromethyl substitution and fluorination of cyclooctynes lead to improved reactivity, in conjunction with increased exothermicity and decreased activation energy values. On the other hand, quantum theory of atoms in molecules computations were performed on some key bond and ring critical points that demonstrated the stabilizing topological properties of electron density and its derivatives upon trifluoromethyl substitution and fluorination of propargylic carbon of cyclooctynes which can be regarded as the essential origin of enhanced reactivity.

scholarly journals Remarkable electronic effect on the total stereoselectivity of the cycloaddition reaction of arylnitrile oxides with pyrrol-2-one derivatives

2019 ◽  
Vol 25 (1) ◽  
pp. 60-65
Author(s):  
A Guesmi ◽  
N Ben Hamadi
Keyword(s):  
Transition State ◽  
Hydroxy Group ◽  
Electronic Effect ◽  
Cycloaddition Reaction ◽  
Asymmetric Induction ◽  
Dipolar Cycloaddition ◽  
Electrostatic Repulsion

AbstractThe regiospecific 1,3-dipolar cycloaddition of 1,5-dihydropyrrol-2-one and arylnitrile oxides derivatives have been investigated. The asymmetric induction expected by the chiral centre of the 5-hydroxy-3-methyl-1,5-dihydropyrrol-2-one derivatives was very effective, single diastereoisomers anti-3 was formed. The diastereoselectivity was linked to the destabilization of the syn transition state as a result of the electrostatic repulsion between the hydroxy group of the dihydropyrrol-2-one derivatives and the atom oxygen of the dipole.

scholarly journals Understanding the mechanism of the 1,3-dipolar cycloaddition reaction between a thioformaldehyde S-oxide and cyclobutadiene: Competition between the stepwise and concerted routes

2019 ◽  
Vol 44 (3) ◽  
pp. 213-221
Author(s):  
Bita Mohtat ◽  
Seyyed Amir Siadati ◽  
Mohammad A Khalilzadeh
Keyword(s):  
Transition State ◽  
Cycloaddition Reaction ◽  
Dipolar Cycloaddition ◽  
Theoretical Methods ◽  
One Step

Changing the mechanism of the widely used 1,3-dipolar cycloaddition reaction from its usual asynchronous one-step pattern to the rarely observed stepwise form leads to the emergence of intermediates, side products, and other impurities. Thus, it is crucial to determine the nature of the mechanism of the 1,3-dipolar cycloaddition reaction between a special 1,3-dipole and a specified dipolarophile (by theoretical methods) before using them for synthesizing a desired product. In this study, therefore, we have investigated the possibility of some probable intermediates emergence in the 1,3-dipolar cycloaddition reaction between cyclobutadiene and thioformaldehyde S-oxide. The results showed that emergence of Int (B) (−52.1 kcal mol−1) via transition state (B-1) is favorable both thermodynamically and kinetically (in comparison with all other stepwise routes). That is, developing probable impurities should not be neglected at least in the cases of the reactions between some thioformaldehyde S-oxide and some dipolarophiles.

New Pyrrolo[1,2-b]pyridazine Derivatives by 1,3-Dipolar Cycloaddition of Mesoionic Oxazolopyridazinone

2008 ◽  
Vol 59 (11) ◽  
Author(s):  
Miron Teodor Caproiu ◽  
Florea Dumitrascu ◽  
Mino R. Caira
Keyword(s):  
Nmr Spectroscopy ◽  
Elemental Analysis ◽  
Cycloaddition Reaction ◽  
Dipolar Cycloaddition ◽  
Pyridazine Derivatives ◽  
New Compounds

New pyrrolo[1,2-b]pyridazine derivatives 8a-f were synthesized by 1,3-dipolar cycloaddition reaction between mesoionic 1,3-oxazolo[3,2-b]pyridazinium-2-oxides and diethyl or diisopropyl acetylenedicarboxylate as alkyne dipolarophiles. The structures of the new compounds were assigned by elemental analysis and NMR spectroscopy.

Copper-catalyzed Convenient Synthesis and SAR Studies of Substituted-1,2,3-triazole as Antimicrobial Agents

2018 ◽  
Vol 16 (1) ◽  
pp. 3-10
Author(s):  
Aniket P. Sarkate ◽  
Kshipra S. Karnik ◽  
Pravin S. Wakte ◽  
Ajinkya P. Sarkate ◽  
Ashwini V. Izankar ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Antifungal Activity ◽  
Antimicrobial Agents ◽  
Cycloaddition Reaction ◽  
Dipolar Cycloaddition ◽  
One Pot ◽  
Triazole Derivatives ◽  
Sar Studies ◽  
Convenient Synthesis ◽  
Antibacterial And Antifungal

Background:A novel copper-catalyzed synthesis of substituted-1,2,3-triazole derivatives has been developed and performed by Huisgen 1,3-dipolar cycloaddition reaction of azides with alkynes. The reaction is one-pot multicomponent.Objective:We state the advancement and execution of a methodology allowing for the synthesis of some new substituted 1,2,3-triazole analogues with antimicrobial activity.Methods:A series of triazole derivatives was synthesized by Huisgen 1,3-dipolar cycloaddition reaction of azides with alkynes. The structures of the synthesized compounds were elucidated and confirmed by 1H NMR, IR, MS and elemental analysis. All the synthesized compounds were tested for their antimicrobial activity against a series of strains of Bacillus subtilis, Staphylococcus aureus and Escherichia coli for antibacterial activity and against the strains of Candida albicans, Aspergillus flavus and Aspergillus nigar for antifungal activity, respectively.Results and Conclusion:From the antimicrobial data, it was observed that all the newly synthesized compounds showed good to moderate level of antibacterial and antifungal activity.

Polar Diels-Alder Reactions Under Microwave Irradiation Employing Different Heterocyclic Compounds as Electrophiles

2019 ◽  
Vol 16 (6) ◽  
pp. 527-543 ◽  
Author(s):  
Pedro M.E. Mancini ◽  
Carla M. Ormachea ◽  
María N. Kneeteman
Keyword(s):  
Organic Synthesis ◽  
Heterocyclic Compounds ◽  
Ionic Conduction ◽  
Theoretical Calculations ◽  
Cycloaddition Reaction ◽  
Diels Alder ◽  
The Other ◽  
Conventional Heating ◽  
Protic Ionic Liquids ◽  
Solvent Free Conditions

During the last twenty years, our research group has been working with aromatic nitrosubstituted compounds acting as electrophiles in Polar Diels-Alder (P-DA) reactions with different dienes of diverse nucleophilicity. In this type of reaction, after the cycloaddition reaction, the nitrated compounds obtained as the [4+2] cycloadducts suffer cis-extrusion with the loss of nitrous acid and a subsequent aromatization. In this form, the reaction results are irreversible. On the other hand, the microwave-assisted controlled heating become a powerful tool in organic synthesis as it makes the reaction mixture undergo heating by a combination of thermal effects, dipolar polarization and ionic conduction. As the Diels-Alder (D-A) reaction is one of the most important process in organic synthesis, the microwave (MW) irradiation was applied instead of conventional heating, and this resulted in better yields and shorter reaction times. Several substituted heterocyclic compounds were used as electrophiles and different dienes as nucleophiles. Two experimental situations are involved: one in the presence of Protic Ionic Liquids (PILs) as solvent and the other under solvent-free conditions. The analysis is based on experimental data and theoretical calculations.

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