Hydrogen transfer in the retro diels-alder fragmentation of oxygen-containing heterocyclic compounds. II—Chromones

1979 ◽  
Vol 14 (7) ◽  
pp. 345-349 ◽  
Author(s):  
Shizuko Eguchi
Keyword(s):  
Heterocyclic Compounds ◽  
Hydrogen Transfer ◽  
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.

Hetero Diels–Alder reactions of o-thioquinones with cyclic dienes: an efficient synthesis of novel heterocyclic compounds

Tetrahedron ◽  
2001 ◽  
Vol 57 (39) ◽  
pp. 8349-8356 ◽  
Author(s):  
Vijay Nair ◽  
Bini Mathew ◽  
Nigam P Rath ◽  
M Vairamani ◽  
S Prabhakar
Keyword(s):  
Heterocyclic Compounds ◽  
Diels Alder ◽  
Efficient Synthesis ◽  
Cyclic Dienes

Novel Synthesis of Heterocyclic Compounds Having Angular Nitrogen Atom by Intramolecular Diels-Alder Reaction of 1-1-Azadienes

Heterocycles ◽  
1985 ◽  
Vol 23 (1) ◽  
pp. 221 ◽  
Author(s):  
Tetsuji Kametani ◽  
Masataka Ihara ◽  
Akihiro Kawaguchi ◽  
Tomoko Kirihara ◽  
Keiichiro Fukumoto
Keyword(s):  
Nitrogen Atom ◽  
Heterocyclic Compounds ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Novel Synthesis

scholarly journals Synthesis of Novel N-Heterocyclic Compounds Containing 1,2,3-Triazole Ring System via Domino, “Click” and RDA Reactions

Molecules ◽  
2019 ◽  
Vol 24 (4) ◽  
pp. 772 ◽  
Author(s):  
Márta Palkó ◽  
Mohamed El Haimer ◽  
Zsanett Kormányos ◽  
Ferenc Fülöp
Keyword(s):  
Heterocyclic Compounds ◽  
Click Reaction ◽  
Triazole Ring ◽  
Heterocyclic Ring ◽  
Ring System ◽  
Diels Alder ◽  
Ring Closure ◽  
Synthetic Route ◽  
13C Nuclear Magnetic Resonance ◽  
Nmr Methods

An uncomplicated, high-yielding synthetic route has been developed to constitute complicated heterocycles, applying domino, click and retro-Diels–Alder (RDA) reaction sequences. Starting from 2-aminocarboxamides, a new set of isoindolo[2,1-a]quinazolinones was synthesized with domino ring closure. A click reaction was performed to create the 1,2,3-triazole heterocyclic ring, followed by an RDA reaction resulting in dihydropyrimido[2,1-a]isoindole-2,6-diones. The absolute configuration, concluded by the norbornene structure that served as a chiral source, remained constant throughout the transformations. The structure of the synthesized compounds was examined by 1H and 13C Nuclear Magnetic Resonance (NMR) methods.

Why Do Five-Membered Heterocyclic Compounds Sometimes Not Participate in Polar Diels–Alder Reactions?

2013 ◽  
Vol 78 (6) ◽  
pp. 2462-2471 ◽  
Author(s):  
Luis R. Domingo ◽  
Patricia Pérez ◽  
Daniela E. Ortega
Keyword(s):  
Heterocyclic Compounds ◽  
Diels Alder

Flavan derivatives. XXV. Mass spectra of 3-hydroxyflavanones, flavan-3-ols, and flavan-3,4-diols

1968 ◽  
Vol 21 (12) ◽  
pp. 3025 ◽  
Author(s):  
JW Clark-Lewis
Keyword(s):  
Mass Spectra ◽  
Hydrogen Transfer ◽  
Diels Alder ◽  
Hydroxyl Group ◽  
Mass Spectral Data ◽  
Insertion Technique ◽  
Mass Spectral ◽  
Marked Enhancement ◽  
Characteristic Fragmentation ◽  
Fragmentation Patterns

Mass spectral data are reported for eight 3-hydroxyflavanones, ten flavan-3-ols, and twelve flavan-3,4-diol derivatives. The principal fragmentation of each of these three classes of compound yields ions derived by retro Diels-Alder fission of the heterocyclic nucleus, accompanied in the case of 3-hydroxyflavanones and flavan-3-ols by hydrogen transfer from the 3-hydroxyl group to the A ring fragment. Deuteration experiments with flavan-3-ols confirmed the origin of the hydrogen atom transferred. Flavan-3,4-diols show two characteristic fragmentation patterns depending on the insertion technique. Mass spectra obtained by indirect insertion of flavan-3,4-diols showed a very marked enhancement of the intensities of the M-18 and M-18-28 peaks, and of their fragmentation ions, compared with spectra obtained by direct insertion.

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