Cycloaddition Reactions of Arylmethylenemalonaldehydes with Olefins

1992 ◽  
Vol 57 (11) ◽  
pp. 2337-2358 ◽  
Author(s):  
Dalimil Dvořák ◽  
David Šaman ◽  
Zdeněk Arnold ◽  
Ivana Císařová ◽  
Václav Petříček
Keyword(s):  
Nmr Spectroscopy ◽  
Carboxylic Acid ◽  
Vinyl Ether ◽  
Aromatic Nucleus ◽  
Ethyl Vinyl Ether ◽  
Cycloaddition Reactions ◽  
Ethyl Vinyl ◽  
X Ray ◽  
H Nmr ◽  
Conformational Equilibria

A series of 2,4-disubstituted 3,4-dihydro-2H-pyran-5-carboxaldehydes II-XIX was prepared by reaction of substituted arylmethylenemalonaldehydes I with 2-methylpropane, 1,1-diphenylethylene, styrene, ethyl vinyl ether, 1,1-dimethoxyethylene and 1,1-bis(methylthio)ethylene. In the case of the reaction with ethyl vinyl ether the dependence of the ratio of the arising cis- and trans- 2-ethoxy-4-aryl-3,4-dihydropyran-5-carboxaldehydes VII-XIV on the substitutent on the aromatic nucleus was studied. Information on the mechanism of this reaction was obtained and conformational equilibria of 2-ethoxy-4-aryl-3,4-dihydropyran-5-carboxaldehydes in solution were studied by 1H NMR spectroscopy. The structure of trans-2-ethoxy-4-(4-chlorophenyl)-3,4-dihydropyran-5-carboxaldehyde (trans-VIII) was confirmed by X-ray analysis of the corresponding carboxylic acid trans-XXII.

A Facile Synthesis of 2,6-Dideoxy 6,6,6-Trifluorinated Carbohydrate Analogues

1998 ◽  
Vol 51 (7) ◽  
pp. 545 ◽  
Author(s):  
Colin M. Hayman ◽  
David S. Larsen ◽  
Sally Brooker
Keyword(s):  
Vinyl Ether ◽  
Boron Trifluoride Etherate ◽  
Diels Alder ◽  
Ethyl Vinyl Ether ◽  
Similar Reaction ◽  
X Ray Diffraction ◽  
Facile Synthesis ◽  
Ethyl Vinyl ◽  
X Ray ◽  
Structural Assignment

The syntheses of 2,6-dideoxy-6,6,6-trifluoro-DL-arabino-hexose (4) and the corresponding glycoside, ethyl 2,6-dideoxy-6,6,6-trifluoro-DL-arabino-hexopyranoside (11), are described. The key step in the synthesis of (4) involved the Lewis acid catalysed hetero-Diels–Alder reactions of (E)-4-benzyloxy-1,1,1-trifluorobut-3-en-2-one and benzyl vinyl ether. Hydroboration of the resulting cycloadduct, and hydrogenylitic debenzylation gave (4) in a 59% overall yield. The ethyl glycoside (11) was prepared in a similar manner from ethyl vinyl ether. A single-crystal X-ray diffraction study confirmed the structural assignment of (11). The O-glycosides (17) and (18) were formed from the boron trifluoride etherate promoted reaction of the per-acetate of (4), i.e. (16), and 2-naphthol. However, a similar reaction between 5-hydroxy-1,4-dimethoxynaphthalene and (16) gave the disubstituted C-glycoside (19) in 52% yield.

scholarly journals Diastereoselective synthesis of nitroso acetals from (S,E)-γ-aminated nitroalkenes via multicomponent [4 + 2]/[3 + 2] cycloadditions promoted by LiCl or LiClO4

2013 ◽  
Vol 9 ◽  
pp. 838-845 ◽  
Author(s):  
Leandro Lara de Carvalho ◽  
Robert Alan Burrow ◽  
Vera Lúcia Patrocinio Pereira
Keyword(s):  
Vinyl Ether ◽  
Ethyl Vinyl Ether ◽  
Diffraction Experiment ◽  
Diastereoselective Synthesis ◽  
X Ray Diffraction ◽  
Chiral Compound ◽  
Ethyl Vinyl ◽  
X Ray ◽  
Organic Solutions

Chiral nonracemic aminated nitroso acetals were synthesized via diastereoselective multicomponent [4 + 2]/[3 + 2] cycloadditions employing new (S,E)-γ-nitrogenated nitroalkenes 5a–c as heterodienes, ethyl vinyl ether (EVE) as a dienophile, and selected electron-deficient alkenes as 1,3-dipolarophiles. The employment of different organic solutions of LiClO4 or LiCl as promoter systems provided the respective nitroso acetals with yields from 34–72% and good levels of diastereoselectivity. In addition, the nitroso acetal 9c was transformed to the pyrrolizidin-3-one derivative 14c, proving the usefulness of the route in the synthesis of an interesting chiral compound. The elucidation of the stereostructures was based on 2D COSY, NOESY and HSQC NMR experiments as well as an X-ray diffraction experiment.

scholarly journals Electron Release and Proton Acceptance Reactions of (dpp-BIAN)Mg(THF)3

2008 ◽  
Vol 63 (2) ◽  
pp. 161-168 ◽  
Author(s):  
Igor L. Fedushkin ◽  
Valentina A. Chudakova ◽  
Markus Hummert ◽  
Herbert Schumann
Keyword(s):  
Nmr Spectroscopy ◽  
Carboxylic Acid ◽  
Ir Spectroscopy ◽  
The Other ◽  
X Ray ◽  
H Nmr ◽  
Trigonal Bipyramidal ◽  
Electron Release ◽  
Coordination Spheres ◽  
Centrosymmetric Dimers

(dpp-BIAN)Mg(THF)3 (1) (dpp-BIAN = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) and (PhCOO)2 react with splitting of the peroxide bridge and formation of the dimeric magnesium benzoate [(dpp-BIAN)MgOCOPh(THF)]2 (2). The reaction of 1 with PhCOOH yields the dimeric magnesium benzoate [(dpp-BIAN)(H)MgOCOPh(THF)]2 (3), whereas 1 and furanyl-2-carboxylic acid react with liberation of hydrogen and formation of (dpp-BIAN)Mg[OCO(2-C4H3O)]2 Mg(dpp-BIAN)(THF) (4). Compounds 2, 3, and 4 have been characterized by elemental analysis, IR spectroscopy, and X-ray structure analysis, compound 3 also by 1H NMR spectroscopy. The eightmembered metallacycles of the centrosymmetric dimers 2 and 3 are almost completely planar. The two magnesium atoms in 4 show different coordination spheres; one is surrounded by its ligands in a trigonal bipyramidal manner, the other one in a tetrahedral fashion. The Mg···Mg separations in 2, 3 and 4 are 4.236, 4.296, and 4.030 Å, respectively

Formation of furofurans from tetraacetylethylene. Molecular and crystal structure of a spiro[furan-2(5H),2′(3′H)-furo[2,3-b]furan]

1980 ◽  
Vol 58 (16) ◽  
pp. 1645-1650 ◽  
Author(s):  
Giorgio Adembri ◽  
Donato Donati ◽  
Renzo Cini ◽  
Rodolfo Nesi ◽  
Mirella Scotton
Keyword(s):  
Crystal Structure ◽  
Vinyl Ether ◽  
Furan Ring ◽  
Ring Closure ◽  
Molecular And Crystal Structure ◽  
Ethyl Vinyl Ether ◽  
Furan Derivative ◽  
Ethyl Vinyl ◽  
X Ray

Dimerization of tetraacetylethylene (TAE) 1 has led to a spiro[furan-2(5H),2′(3′H)-furo[2,3-b]furan], whose structure was established by X-ray analysis. The trend of TAE to furan ring closure was confirmed by the reaction with ethyl vinyl ether, where the first product of the reaction, the pyran adduct 8, smoothly rearranged to a furo[2,3-b]furan derivative 9.

Computational Study on the Mechanism of Cycloaddition Reactions of Bissulfonyl-1,3-butadiene with Some Alkenes

2020 ◽  
Vol 17 (10) ◽  
pp. 735-742
Author(s):  
Sepideh Masoumifar ◽  
Mina Haghdadi ◽  
Hassan Ghasemnejad Bosra
Keyword(s):  
Vinyl Ether ◽  
Energy Barrier ◽  
Computational Study ◽  
Cycloaddition Reaction ◽  
Dft Method ◽  
Ethyl Vinyl Ether ◽  
Cycloaddition Reactions ◽  
Ethyl Vinyl

The cycloaddition reactions of 2,3-bis (ethylene sulfonyl)-1,3-butadiene with 2,3-dimethyl- 1,3-butadiene, cyclopentadiene, 2-methyl prop-2-enoate and ethyl vinyl ether have been theoretically studied using the DFT method at the MPWB1K/cc-pVDZ level of theory. There are two possible modes of participation in each reaction (2π and 4π electron), of which the 2π electron is preferred. The energy results indicate that formations of the [2+4] cycloadducts are favored kinetically. The stereoselectivity of the [2+4] cycloaddition reaction of 2,3-bis (ethylene sulfonyl)-1,3-butadiene with cyclopentane is the highest and the energy barrier for this process is the lowest.

[4 + 2] and [3 + 2] Cycloaddition reactions of 2',3'-dideoxy-3'-nitro-2',3'-didehydrothymidine with ethyl vinyl ether

1993 ◽  
Vol 58 (10) ◽  
pp. 2874-2879 ◽  
Author(s):  
Alexander Papchikhin ◽  
Peter Agback ◽  
Janez Plavec ◽  
Jyoti Chattopadhyaya
Keyword(s):  
Vinyl Ether ◽  
Ethyl Vinyl Ether ◽  
Cycloaddition Reactions ◽  
Ethyl Vinyl

Reactions of 2-phenyl-4H-1,3,2-benzodioxaborin, a stable ortho-quinone methide precursor

1992 ◽  
Vol 70 (6) ◽  
pp. 1717-1732 ◽  
Author(s):  
Jeffrey D. Chambers ◽  
Jason Crawford ◽  
Haydn W. R. Williams ◽  
Claude Dufresne ◽  
John Scheigetz ◽  
...  
Keyword(s):  
Vinyl Ether ◽  
Lewis Acid ◽  
Quinone Methide ◽  
Ethyl Vinyl Ether ◽  
Cycloaddition Reactions ◽  
Substituted Phenols ◽  
Quinone Methides ◽  
Ethyl Vinyl ◽  
Aryl Group ◽  
Intramolecular Reaction

Thermolysis of 1-phenyl-4H-1,3,2-benzodioxaborins generated the corresponding ortho-quinone methides, which were found to undergo intermolecular cycloaddition reactions with ethyl vinyl ether, dihydropyran, β-methylstyrene, cyclohexene, and 1-ethoxy-1-z-trimethylsiloxy-1-propenes to give various substituted chromans. Intramolecular trapping of the quinone methides with an olefin led to the syntheses of several analogs of tetrahydrocannabinols. ortho-Quinone methides, generated by treatment of the 2-phenyl-4H-1,3,2-benzodioxaborins with a Lewis acid, react with various nucleophiles to give the corresponding 1,4-addition products. Thus, alkyl and aryl thiols, alcohols, amine, hydride, allyl trimethylsilane, acetophenone, and diethylmalonate as well as some aryl compounds react with the quinone methide to give various 2-substituted phenols. Intramolecular reaction of the quinone methide with an aryl group led to the preparation of some 4-phenylchromans and tetralins.

scholarly journals Tautomerisation in 1-(4-Methylphenylazo)naphthalen-2-ol and 2-(4-Methylphenylazo)-4-methylphenol: A Crystallographic and 13C{1H}NMR Study

1999 ◽  
Vol 23 (3) ◽  
pp. 178-179
Author(s):  
Wendy I. Cross ◽  
Kevin R. Flower ◽  
Robin G. Pritchard
Keyword(s):  
Acetic Acid ◽  
Nmr Spectroscopy ◽  
Resonant Frequency ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Nmr Study ◽  
Acetic Acid Esters ◽  
Acid Esters ◽  
Equivalent Carbon

The acetic acid esters of 1-(4-methylphenylazo)naphthalen-2-ol 1 and 2-(4-methylphenylazo)-4-methylphenol 3 are prepared and characterised by single crystal X-ray diffraction studies and 13C{1H}NMR spectroscopy; the position of the C(2)13C resonance for the ester is used to predict the position of resonant frequency of the equivalent carbon in the parent alcohols and hence, calculate the position of the azo-hydrazone equilibrium in these compounds.

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