Results 191 to 200 of about 18,263,514 (224)
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Stereospecificity of 1,.3-dipolar cycloadditions of cyclic nitrones to (E) and (Z)-β-nitrostyrenes
Tetrahedron, 1987Abstract 3,4-Dihydroisoquinoline-N-oxide (1) reacted readily with (E)-s-nitrostyrene in a regiospecific reaction to give a mixture of 4-nitro-5-phenylisoxazolidines 3a and 4a resulting from endo and exo (with respect to the nitro group) transition states, respectively. This cycloaddition was found reversible under mild conditions. A careful study
Marina Burdisso +3 more
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Intramolecular 1, 3-dipolar cycloadditions of the new sydnone derivatives
2005Inter- and intramolecular photochemical [2+2] cycloaddition reactions of o-substituted divinylbenzene with furan and pyrrole rings give various hetero polycyclic compounds (1). The photochemical reaction of the sydnone analogue 1 did not undergo intramolecular cycloaddition (2), but in the presence of acrolein, the intermolecular 1, 3-dipolar ...
Butković, Kristina +2 more
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Phosphorous and Sulfur and the Related Elements, 1986
Abstract Nitrile sulphides, generated by thermal decarboxylation of 1,3,4-oxathiazol-2-ones, undergo 1,3-dipolar cycloaddition to trichloroacetonitrile yielding 5-trichloromethyl-1,2,4-thiadiazoles (45-66%). The reaction of the cycloadducts with secondary amines has also been examined.
Derek J. Greig +3 more
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Abstract Nitrile sulphides, generated by thermal decarboxylation of 1,3,4-oxathiazol-2-ones, undergo 1,3-dipolar cycloaddition to trichloroacetonitrile yielding 5-trichloromethyl-1,2,4-thiadiazoles (45-66%). The reaction of the cycloadducts with secondary amines has also been examined.
Derek J. Greig +3 more
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Journal of Heterocyclic Chemistry, 1996
Abstract1‐(Azidomethyl)benzotriazole reacts with alkynes to give mixtures of isomeric 1,2,3‐triazoles, whereas the interactions of 1‐(azidomethyl)benzotriazole and ‐5‐phenyl‐1,2,3,4‐tetrazole with alkenes proceed regioselectively to form 1,2,3‐triazolines and/or aziridines and enamines in good yields.
Alan R. Katritzky +3 more
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Abstract1‐(Azidomethyl)benzotriazole reacts with alkynes to give mixtures of isomeric 1,2,3‐triazoles, whereas the interactions of 1‐(azidomethyl)benzotriazole and ‐5‐phenyl‐1,2,3,4‐tetrazole with alkenes proceed regioselectively to form 1,2,3‐triazolines and/or aziridines and enamines in good yields.
Alan R. Katritzky +3 more
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J. Chem. Soc., Perkin Trans. 1, 1991
The 1,3-dipolar cycloaddition between ethyl trifluoroacetoacetate and N-(benzylidene)methylamine Noxide, performed in boiling toluene, leads regio- and stereo-selectively to an isoxazolidine, while the corresponding ethyl acetoacetate is found to be unreactive under the same conditions.
Jean-Pierre Bégué +2 more
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The 1,3-dipolar cycloaddition between ethyl trifluoroacetoacetate and N-(benzylidene)methylamine Noxide, performed in boiling toluene, leads regio- and stereo-selectively to an isoxazolidine, while the corresponding ethyl acetoacetate is found to be unreactive under the same conditions.
Jean-Pierre Bégué +2 more
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Approach to regiochemistry using local softness in 1,3-dipolar cycloadditions
Journal of Computational Chemistry, 1998The principle of hard and soft acids and bases is applied in the local sense to rationalize the regiochemistry in the cycloaddition reactions of a few typical 1,3-dipoles, in particular those with phosphorus-containing dipolarophiles. Local softnesses are calculated using density functional theory.
Asit K. Chandra, Minh Tho Nguyen
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Gram Scale Synthesis of (±)-Gregatin A via 1, 3-dipolar Cycloaddition Strategy
Here, we present a 6-step gram-scale synthesis of (±)-gregatin A, a fungal polyketide characterized by an alkylated furanone core origi-nally isolated from Cephalosporium gregatum. The synthetic route features an intermolecular 1,3-dipolar cycloaddition, a Mo-mediated disconnection of isoxazole skeleton, and an acid-mediated desilylation/enamine ...Yiming Ding +7 more
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2 + 3 Dipolar cycloadditions of a monomeric thioaldehyde
The Journal of Organic Chemistry, 1986E. Vedejs, R. G. Wilde
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2003
This paper announces the results of certain 1, 3-dipolar cycloadditions to polycyclic aromatic hydrocarbons (PAHs). The 1, 3-dipoles generated from cyclobutene diester epoxides thermally reacted with PAHs to give cycloadducts. This reaction demonstrated the remarkable ability of these 1, 3-dipoles to disrupt an aromatic system by adding across specific
Margetić, Davor +2 more
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This paper announces the results of certain 1, 3-dipolar cycloadditions to polycyclic aromatic hydrocarbons (PAHs). The 1, 3-dipoles generated from cyclobutene diester epoxides thermally reacted with PAHs to give cycloadducts. This reaction demonstrated the remarkable ability of these 1, 3-dipoles to disrupt an aromatic system by adding across specific
Margetić, Davor +2 more
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Synthesis of Isoxazoles via [2+3]-Dipolar Cycloaddition Using Alkyne Surrogates
Synfacts, 2007A. II, S. Dadiboyena, J. Xu
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