Sequential Intramolecular Diels-Alder Reaction and Intermolecular 1,3-Dipolar Cycloaddition Reaction: One-pot [6.6.5]Annelation Reaction Leading to the Formation of Polyazasteroid Type Skeletons

Heterocycles ◽  
1986 ◽  
Vol 24 (3) ◽  
pp. 629 ◽  
Author(s):  
Otohiko Tsuge ◽  
Kazunori Ueno ◽  
Shuji Kanemasa
2014 ◽  
Vol 79 (8) ◽  
pp. 911-924 ◽  
Author(s):  
Mahshid Hamzehloueian ◽  
Saeid Yeganegi ◽  
Yaghoub Sarrafi ◽  
Kamal Alimohammadi ◽  
Marzieh Sadatshahabi

The present study reports a systematic computational analysis of the two possible pathways, fused and bridged, for an intramolecular hetero Diels-Alder (IMHDA) and an intramolecular 1,3-dipolar cycloaddition (IMDCA) of 2-vinyloxybenzaldehyde derivatives. The potential energy surface analysis for both reactions is in agreement with experimental observations. The activation energies associated with the two regioisomeric channels in IMHDA reaction show that the bridged product is favored, although in IMDCA, the most stable TS results the fused product. The global electronic properties of fragments within each molecule were studied to discuss the reactivity patterns and charge transfer direction in the intramolecular processes. The asynchronicity of the bond formation and aromaticity of the optimized TSs in the Diels-Alder reaction as well as cycloaddition reaction were evaluated. Finally, 1H NMR chemical shifts of the possible regioisomers have been calculated using the GIAO method which of the most stable products are in agreement with the experimental data in the both reaction.


2011 ◽  
Vol 16 (2) ◽  
pp. 160 ◽  
Author(s):  
John H. Bermudez ◽  
José Luis Pinto ◽  
Carlos Mario Meléndez ◽  
José A. Henao ◽  
Vladimir V. Kouznetsov

<p><strong>Objectives. </strong>To prepare new N-(1,2,3,4-tetrahydroquinolin-4-yl) pyrrolidin-2-one molecules and to characterize them by spectroscopic methods. <strong>Materials and methods. </strong>All reagents were purchased from Aldrich, commercial grade. The purity of the products and the composition of the reaction mixtures were monitored by thin layer chromatography over Silufol UV<sub>254</sub> chromatoplates (0.25 mm). Product isolation and purification were performed by column chromatography (SiO<sub>2</sub>), using ethyl acetate. <strong>Results.</strong> Preparation of new N-(2-nitrophenyl-1,2,3,4-tetrahydroquinolin-4-yl) pyrrolidin-2-ones has been achieved via the one-pot synthesis, based on a BiCl<sub>3</sub>-catalyzed imino Diels-Alder cycloaddition reaction of toluidine, N-vinylpyrrolidin-2-one and 4-nitro- or 3-nitrobenzaldehydes. The structure of the pyrrolidine derivatives was confirmed by <sup>1</sup>H nmr and <sup>13</sup>C nmr studies, in addition to inverse-detected 2D NMR experiments and monocrystal X-ray diffraction. <strong>Conclusions. </strong>An efficient, economic, and fast synthetic route (multi-component imino Diels-Alder reaction) was employed in the construction of several new tetrahydroquinoline derivatives, useful and attractive rigid skeleton with well-defined stereochemistry.</p> <p> </p> <p><strong>Key words: </strong>tetrahydroquinoline derivatives, N-substituted pyrrolidin-2-ones, three component imino Diels-Alder reaction, one-pot synthesis.</p>


2014 ◽  
Vol 10 (6) ◽  
pp. 951-960
Author(s):  
Orazio Attanasi ◽  
Luca Bianchi ◽  
Maurizio D’Auria ◽  
Gianfranco Favi ◽  
Fabio Mantellini ◽  
...  

1997 ◽  
Vol 52 (7) ◽  
pp. 851-858 ◽  
Author(s):  
Gunther Seitz ◽  
Johanna Siegl

The anomeric imido esters 5 and 6, appropriate precursors for C-nucleoside synthesis, were prepared and utilized as heterodienophiles in a Diels-Alder reaction with inverse electron demand to yield the novel, protected 1.2.4-triazine C-nucleosides 8 and 9. They could be deprotected by treatment with 70% trifluoroacetic acid to furnish the free C-nucleosides 10 and 11. The triazine „aglycon“ of 8 contains an electron deficient diazadiene system, highly activated to react with various electron rich dienophiles such as enamines, enol ethers and several cyclic ketene acetals in an „inverse“ [4+2]-cycloaddition reaction. The Diels-Alder adducts spontaneously eliminate N2 and after follow-up reactions the O-TBDPS protected pyridine-C-nucleosides 13, 15, 17,19, 21 and 23 are formed. Removal of the protecting group by treatment with CF3CO2H /H2O leads to the corresponding 2’,3’-dideoxy-β-D-ribofuranosyl- pyridines.


2020 ◽  
Author(s):  
Haruyasu Asahara ◽  
Minami Hiraishi ◽  
Nagatoshi Nishiwaki

β-Nitrostyrenes underwent the Diels-Alder reaction with Danishefsky’s diene to afford cyclohexenes together with the corresponding hydrolyzed products, 3-arylated 5-methoxy-4-nitrocyclohexanones. When the reaction was conducted in the presence of water, the cyclohexenes were efficiently hydrolyzed into cyclohexanones. Subsequent aromatization by heating the cyclohexanone with a catalytic amount of iodine in dimethyl sulfoxide gave 3-arylated 4-nitrophenols. The reaction of nitrostyrenes with Danishefsky’s diene could be conducted in one-pot to directly afford the corresponding nitrophenols. Moreover, a heteroaryl group such as a thienyl group could be introduced into the nitrophenol framework.


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