Identification of Diels-Alder regioisomers by mass spectrometry coupled with theoretical calculations

1993 ◽  
Vol 28 (7) ◽  
pp. 752-758 ◽  
Author(s):  
C. Cativiela ◽  
J. I. García ◽  
J. Garín ◽  
J. A. Mayoral ◽  
J. Orduna ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Theoretical Calculations ◽  
Diels Alder

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.

scholarly journals Mass spectral and theoretical investigations of the transient proton-bound dimers on the cleavage processes of the peptide GHK and its analogues

RSC Advances ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 4077-4086
Author(s):  
Jinhu Wang ◽  
Cheng Wang ◽  
Han Zhang ◽  
Yang Liu ◽  
Tiesheng Shi
Keyword(s):  
Mass Spectrometry ◽  
Theoretical Calculations ◽  
Mass Spectral ◽  
Protonated Peptides ◽  
Fragmentation Mechanisms ◽  
Theoretical Investigations

Fragmentation mechanisms of the singly protonated peptides GHK, GHKH and HGHK have been investigated by mass spectrometry and theoretical calculations.

Vacuum ultraviolet photochemistry of the conformers of the ethyl peroxy radical

2021 ◽  
Vol 23 (38) ◽  
pp. 22096-22102
Author(s):  
Zuoying Wen ◽  
Xiaoxiao Lin ◽  
Xiaofeng Tang ◽  
Bo Long ◽  
Chengcheng Wang ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Vacuum Ultraviolet ◽  
Theoretical Calculations ◽  
Peroxy Radical ◽  
Photoionization Mass Spectrometry ◽  
Condon Factors ◽  
Vuv Photoionization ◽  
Franck Condon

C2H5O2 plus its gauche and trans conformers are studied using synchrotron-based VUV photoionization mass spectrometry and theoretical calculations, and it is found that the gauche conformer has favorable Franck–Condon factors in photoionization.

Condensed, solution and gas phase behaviour of mono- and dinuclear 2,6-diacetylpyridine (dap) hydrazone copper complexes probed by X-ray, mass spectrometry and theoretical calculations

2013 ◽  
Vol 42 (32) ◽  
pp. 11497 ◽  
Author(s):  
Brenno A. D. Neto ◽  
Barbara F. L. Viana ◽  
Thyago S. Rodrigues ◽  
Priscila M. Lalli ◽  
Marcos N. Eberlin ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Copper Complexes ◽  
Theoretical Calculations ◽  
Phase Behaviour ◽  
X Ray

Vinylindenes and some heteroanalogues in the Diels-Alder reaction. II. Substituted fluorenes from 3-vinylindenes

1977 ◽  
Vol 30 (5) ◽  
pp. 1061 ◽  
Author(s):  
R Bergamasco ◽  
QN Porter
Keyword(s):  
Mass Spectrometry ◽  
Maleic Anhydride ◽  
Alder Reaction ◽  
Diels Alder ◽  
Dimethyl Acetylenedicarboxylate ◽  
Diels Alder Reaction

3-Vinylindene, 2-methyl-3-vinylindene and 3-isopropenylindene give normal, photostable adducts with ethenetetracarbonitrile by a Diels- Alder process. The first diene gives adducts with maleic anhydride, N- phenylmaleimide and dimethyl acetylenedicarboxylate. Where there is stereochemical ambiguity the adducts are shown by mass spectrometry to be exclusively endo. Two heterocyclic analogues are formed from 3- vinylindene with p-toluenesulphonyl cyanide and N-sulphinyl-p- toluenesulphonamide.

Diels-Alder cycloadditions of electron-rich, electron-deficient, and push-pull dienes with cyclic dienophiles: high-pressure-induced reactions and theoretical calculations

1991 ◽  
Vol 56 (13) ◽  
pp. 4135-4141 ◽  
Author(s):  
Vicenc Branchadell ◽  
Mariona Sodupe ◽  
Rosa M. Ortuno ◽  
Antonio Oliva ◽  
Domingo Gomez-Pardo ◽  
...  
Keyword(s):  
High Pressure ◽  
Theoretical Calculations ◽  
Diels Alder
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