- Retro Diels-Alder reaction under mild conditions: Experimental and theoretical studies
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The preliminary experimental and theoretical findings on the rDA reaction under milder reaction conditions were analyzed. It was found that required diene was immediately reacted with various dienophiles in a micellar medium to obtain the respective DA adducts in good yields. It was also found that the yield was considerably decreased even after prolonged refluxing conditions in DCM. The rDA reaction with spirocyclopentadiene as the diene can be carried out under mild reaction conditions. The results show that the lower kinetic barrier for this reaction has been identified as arising from greater stabilization of the transition state resulting from effective orbital interactions involving the cyclopropane bond orbitals.
- Kotha, Sambasivarao,Banerjee, Shaibal,Patil, Mahendra P.,Sunoj, Raghavan B.
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p. 1854 - 1856
(2008/02/07)
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- The Preparation and Reactions of Naphthofuran and Naphthofuran
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The syntheses of 1,3-dihydro-1- and 1,3-dihydro-3-hydroxynaphthofuran are described.Upon treatment with acid, these compounds undergo 1,4-elimination of water to generate the reactive naphthofuran, which is trapped in situ by a variety of dienophiles.Aromatization of the resulting adducts gives access to 2,3-disubstituted phenanthrenes or benzanthracenes.In addition, it has been shown that the hemiacetal, 1,3-dihydro-1-hydroxynaphthofuran, which exists in tautomeric equilibrium with 3-(hydroxymethyl)-2-naphthaldehyde, serves as a convenient source of naphthofuran.This furan can also be trapped by a variety of dienophiles.The resulting Diels-Alder adducts can be aromatized, giving substituted anthracenes.The use of aromatic 1,4-quinones as dienophiles leads to linear polycyclic aromatic quinones of four to seven rings.
- Smith, James G.,Dibble, Peter W.,Sandborn, Richard E.
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p. 3762 - 3768
(2007/10/02)
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- ABSORPTION, LUMINISCENCE, AND POLARISATION SPECTRA OF 1,4-TETRACENEQUINONE
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Absorption electronic spectrum of 1,4-tetracenequinone has been interpreted on the basis of excitation polarisation spectrum of fluorescence and dichroism on oriented polyvinyl alcohol sheet.The theoretical spectrum has been obtained by the PPP method in the approximation of variable integrals βc and γ.
- Gas, Bohuslav,Stepan, Vaclav,Titz, Milos,Kratochvil, Vaclav,Nepras, Milos
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p. 538 - 543
(2007/10/02)
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