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《Tetrahedron letters》1997,38(39):6893-6896
The synthesis of 1-(3,4,5-trimethoxyphenyl)-3-trialkylsiloxy-1,3-butadienes and their Diels-Alder reaction with selected dienophiles at room temperature is described. These aryldienes are useful building blocks for the synthesis of natural and pharmacological active products, as has been shown by the preparation of a tetracyclic ketone needed for the synthesis of new anthracycline analogues. 相似文献
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Second-order rate constants for the Diels-Alder reaction of 90 aromatic hydrocarbons with maleic anhydride, measured spectrophotometrically at 91.5° in 1,2,4-trichlorobenzene, are correlated with various reactivity indices, namely Herndon's structure count ratios, second-order perturbation energies, Brown's paralocalization energies, Hess-Schaad resonance energy differences and Polansky indices. Apart from the latter theory, all methods yield satisfactory correlations, with the Hess-Schaad theory being marginally better. An explanation is given why the Hess-Schaad theory is superior to para-localization theory although both are based on Hückel π-electron energies. The observed regioselectivity is correctly accounted for by all except Polansky's theory which yields incorrect results for certain phenes and starphenes. 相似文献
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Yoshiro Kabayashi Tsutomu Yoshida Yuji Hanzawa Itsumaro Kumadaki 《Tetrahedron letters》1980,21(48):4601-4604
The Diels-Alder reactions of tris(trifluoromethyl)trifluoroacetyl-cyclopropene with dienes gave syn-adducts mainly, due to the electronic effects of the fluorinated substituents. 相似文献
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L. O. Khafizova L. R. Yakupova R. A. Tuktarova V. A. D’yakonov L. M. Khalilov A. G. Ibragimov U. M. Dzhemilev 《Russian Journal of Organic Chemistry》2008,44(9):1311-1315
[4π + 2π]-Cycloaddition of substituted alumina-and magnesacyclopenta-2,4-dienes with such dienophiles as maleic anhydride, N-methylmaleimide, 1,4-benzoquinone, and 1,4-naphthoquinone resulted in the formation of the corresponding fused alumina-and magnesanorbornenes whose hydrolysis gave isobenzofuran, isoindole, naphthalene, and anthracene derivatives in high yields. 相似文献
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《Tetrahedron letters》1986,27(48):5875-5876
Diels-Alder cycloaddition reactions of 1-aryl-4-dimethylamino-2-phenyl-1,3-diazabutadienes with monophenyl and diphenylketenes, resulting in high yields of pyrimidin-6-one derivatives are reported. 相似文献
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The cycloaddition of tetrachlorothiophene-S,S-dioxide to azulene occurs across the 1- and 2-positions to give 1,2,3,4-tetrachlorobenz[a]azulene. 相似文献
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A. S. Kil’met’ev E. E. Shul’ts M. M. Shakirov T. V. Rybalova G. A. Tolstikov 《Russian Journal of Organic Chemistry》2013,49(6):872-885
Substituted salicylaldehydes reacted with ethyl diazoacetate to give ethyl 1-benzofuran-3-carboxylates containing various substituents in the aromatic ring. The Diels-Alder reaction of these compounds with Danishefsky’s diene was regioselective, and it provided an effective method for the construction of the heterocyclic skeleton of hexahydrodibenzo[b,d]furan-7-one or tetrahydrodibenzo[b,d]furan-7-one. The adducts were found to undergo rearrangement to substituted 4′-hydroxybiphenyl-2-yl methyl carbonates during column chromatography on silica gel. 相似文献
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Carreno MC Garcia Ruano JL Urbano A Remor CZ Arroyo Y 《The Journal of organic chemistry》2000,65(2):453-458
Diels-Alder reactions of (SS)-2-(2'-methoxynaphthylsulfinyl)-1, 4-benzoquinone (1b), 2-(p-methoxyphenylsulfinyl)-1,4-benzoquinone (1c), and 2-(p-nitrophenylsulfinyl)-1,4-benzoquinone (1d) with cyclopentadiene are reported. These cycloadditions allowed the highly chemo- and stereoselective formation of both diastereoisomeric endo-adducts resulting from reaction on the unsubstituted double bond C(5)-C(6) of quinones working under thermal and Eu(fod)(3)- or BF(3).OEt(2)-catalyzed conditions. The synthesis of endo-adduct [4aS,5S,8R,8aR,SS]-9d resulting from cycloaddition on the substituted C(2)-C(3) double bond was achieved in a chemo- and diastereoselective way from quinone 1d in the presence of ZnBr(2). The reactivity and selectivity of the process proved to be dependent on the electron density of the arylsulfinyl group. 相似文献
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Application of the “hard and soft” concept to the Woodward-Katz model allows simple and accurate prediction of the structure of the major adduct in Diels-Alder reactions. About 100 examples have been examined. Agreement with experimental results is excellent: therefore, the doubts expressed by Houk et al.36 are groundless.Two special cases deserve mention. First, for compounds with heteroatoms at reactive sites, it is necessary to introduce explicity the overlap integrals in the perturbational treatment. Second, in the reactions between electron-poor dienes and nitrosobenzene derivatives the adjacent lone pairs on N and O play an important role. 相似文献
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Ewa Kesler 《Journal of heterocyclic chemistry》1980,17(5):1113-1113
3-(2-Chloropropyl)-2-oxa-3-azabicyclo[2.2.2]oct-5-ene and 2-oxa-3-azabicyclo[2.2.2]oct-5-ene hydrochloride have been prepared by cycloaddition of 2-chloro-2-nitrosopropane to 1,3-cyclohexadiene and their structure determined by nmr, using a 1H nmr shift reagent. 相似文献
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Grant R. Krow Kevin C. Cannon James T. Carey Yoon B. Lee Steven W. Szczepanski Harri G. Ramjit 《Journal of heterocyclic chemistry》1985,22(1):131-135
The ten possible substitution patterns for N-Ethoxycarbonyl-2-methyl-1,2-dihydropyridines 5 in which one or two olefinic sites are alkyl substituted were synthesized and reacted with N-phenylmaleimide 2 to provide cycloadducts 6. N-Ethoxycarbonyl-5,6-cyclohexyl-2-methyl-1,2-dihydropyridine 51 provided the novel spirocycle 61. 相似文献
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Further examples of the title reaction, discovered by Carlson, Sheppard, and Webster, reveal scope and regiochemistry of the formation of 1,6-dihydropyridazines; all the evidence points to a concerted primary addition. 相似文献