scholarly journals Stepwise radical cation Diels–Alder reaction via multiple pathways

2018 ◽  
Vol 14 ◽  
pp. 704-708 ◽  
Author(s):  
Ryo Shimizu ◽  
Yohei Okada ◽  
Kazuhiro Chiba
Keyword(s):  
Radical Cation ◽  
Alder Reaction ◽  
Diels Alder ◽  
Vinyl Ethers ◽  
Diels Alder Reaction ◽  
Alder Adduct

Herein we disclose the radical cation Diels–Alder reaction of aryl vinyl ethers by electrocatalysis, which is triggered by an oxidative SET process. The reaction clearly proceeds in a stepwise fashion, which is a rare mechanism in this class. We also found that two distinctive pathways, including “direct” and “indirect”, are possible to construct the Diels–Alder adduct.

scholarly journals Crystal structures and conformations of two Diels–Alder adduct derivatives: 1,8-bis(thiophen-2-yl)-14-oxatetracyclo[6.5.1.02,7.09,13]tetradeca-2(7),3,5-trien-10-one and 1,8-diphenyl-14-oxatetracyclo[6.5.1.02,7.09,13] tetradeca-2,4,6-trien-10-one

2015 ◽  
Vol 71 (2) ◽  
pp. 213-216
Author(s):  
S. Gopinath ◽  
P. Narayanan ◽  
K. Sethusankar ◽  
Meganathan Nandakumar ◽  
Arasambattu K. Mohanakrishnan
Keyword(s):  
Crystal Packing ◽  
Rotation Axis ◽  
Alder Reaction ◽  
Ring System ◽  
Diels Alder ◽  
Compound I ◽  
Diels Alder Reaction ◽  
Phenyl Rings ◽  
Axis Parallel ◽  
Alder Adduct

The title compounds, C21H16O2S2(I) and C25H20O2(II), are products of a tandem `pincer' Diels–Alder reaction consisting of [2 + 2] cycloadditions between benzo[c]furan and cyclopentanone. Each comprises a fused tetracyclic ring system containing two five-membered rings (inenvelopeconformations with the O atom as the flap) and six-membered rings (inboatconformations). In addition, two thiophene rings in (I) and two phenyl rings in (II) are attached to the tetracyclic ring system. The cyclopentanone ring adopts atwistedconformation in (I) and anenvelopeconformation in (II). In (I), the thiophene rings are positionally disordered over two sets of sites, with occupancy ratios of 0.901 (2):0.099 (2) and 0.666 (2):0.334 (2). In (II), the oxygen atom of the cyclopentanone ring is rotationally disordered over two sites with an occupancy ratio of 0.579 (4):0.421 (4). The molecular structure of (I) is stabilized by an intramolecular C—H...O hydrogen bond, which generates anS(7) ring motif. In the crystal, the molecules are linkedviaweak C—H...O hydrogen bonds, which generateR22(16) ring motifs in (I) andC(8) chains in (II). In both structures, the crystal packing also features C—H...π interactions. The crystal studied of compound (I) was twinned by non-merohedry. The twin component is related by the twin law [−1 0 0 −0.101 1 −0.484 0 0 −1] operated by a twofold rotation axis parallel to thebaxis. The structure of (I) was refined with a twin scale factor of 0.275 (2).

scholarly journals Hetero Diels-Alder adduct formation between nitrosobenzene and tetra-methyl purpurogallin and its retro-Diels-Alder reaction

2001 ◽  
Vol 12 (4) ◽  
Author(s):  
Daniela Gamenara ◽  
Eduardo Días ◽  
Néstor Tancred ◽  
Horacio Heinzen ◽  
Patrick Moyna ◽  
...  
Keyword(s):  
Alder Reaction ◽  
Adduct Formation ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Alder Adduct

Ab Initio Studies of the Radical Cation Diels−Alder Reaction

1999 ◽  
Vol 121 (28) ◽  
pp. 6730-6736 ◽  
Author(s):  
Udo Haberl ◽  
Olaf Wiest ◽  
Eberhard Steckhan
Keyword(s):  
Ab Initio ◽  
Radical Cation ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction

Synthesis of (±)-epiisopodophyllotoxin

1983 ◽  
Vol 61 (3) ◽  
pp. 573-575 ◽  
Author(s):  
Margaret B. Glinski ◽  
Tony Durst
Keyword(s):  
Title Compound ◽  
Dimethyl Fumarate ◽  
Dimethyl Acetal ◽  
Alder Reaction ◽  
Diels Alder ◽  
Carbon Skeleton ◽  
Diels Alder Reaction ◽  
Alder Adduct

The synthesis of (±)-epiisopodophyllotoxin commencing with 6-bromopiperonal dimethyl acetal is described. The carbon skeleton of isoepipodophyllotoxin was assembled via a Diels–Alder reaction between the hydroxyquinodimethane generated photochemically from 6-(3′,4′,5′-trimethoxybenzyl)-piperonal, obtained from the bromoacetal above, and dimethyl fumarate. This Diels–Alder adduct was converted in five steps into the title compound. The overall yield for the seven steps was 15%.

scholarly journals The Intramolecular Radical Cation Induced Diels-Alder Reaction in the Diene - Diene Format

Molecules ◽  
1997 ◽  
Vol 2 (12) ◽  
pp. 80-86 ◽  
Author(s):  
David Rusterholz ◽  
David Gorman ◽  
Paul Gassman
Keyword(s):  
Radical Cation ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction

Mass-Spectra of Annelated 4H-3,1-Oxazin-4-ones

1989 ◽  
Vol 42 (10) ◽  
pp. 1813 ◽  
Author(s):  
LK Dyall
Keyword(s):  
Electron Impact ◽  
Radical Cation ◽  
Mass Spectra ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Impact Fragmentation

Electron-impact fragmentation of 2-R-4H-3,1-benzoxazin-4-ones involves primary losses of CO2 and R; there is also loss of ketene when R is methyl. The ion RCO+ is a major daughter. Successive losses of CO2and RCN yield an ion m/z 76 formulated as dehydrobenzene radical cation. In the case of 2-methyl-4H-3,1-naphth[2,3-d]oxazin-4-one, the 2,3-dehydronaphthalene ion is produced efficiently, and linked scans (B/E) were used to demonstrate that it loses C4H2 ( diacetylene ) in a retro Diels-Alder reaction.

Diels–Alder reaction of tetraarylcyclopentadienones with benzo[b]thiophene S,S-dioxides: an unprecedented de-oxygenation vs. sulfur dioxide extrusion

2020 ◽  
Vol 56 (97) ◽  
pp. 15317-15320
Author(s):  
Palani Manikandan ◽  
Jayachandran Karunakaran ◽  
Elumalai Varathan ◽  
Georg Schreckenbach ◽  
Arasambattu K Mohanakrishnan
Keyword(s):  
Sulfur Dioxide ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Alder Adduct

The Diels–Alder adduct, dihydrodibenzothiophene S,S-dioxides underwent aromatization either through de-oxygenation or extrusion of sulfur dioxide to furnish substituted dibenzothiophenes or benzenes.

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