Diels-Alder additions of dimethyl acetylenedicarboxylate to sterically hindered cyclohexa-2,4-dienones. Formation and X-ray structure analysis of stereoisomeric bicyclo[2.2.2]octadienones

1983 ◽  
Vol 36 (7) ◽  
pp. 1361 ◽  
Author(s):  
H Becker ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Structure Analysis ◽  
Electronic Absorption ◽  
Spectral Properties ◽  
Diels Alder ◽  
Dimethyl Acetylenedicarboxylate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sterically Hindered

The Diels-Alder addition of dimethyl acetylenedicarboxylate to sterically hindered 2,4-cyclohexadienones (spiro-quinol ethers) gives rise to stereoisomeric bicyclo[2.2.2]octadienones. The structures of three of these have been elucidated by single-crystal X-ray diffraction methods and their 1H n.m.r. and electronic absorption spectral properties are reported.

Structural Study of an Unusual Diels-Alder Adduct

1992 ◽  
Vol 45 (12) ◽  
pp. 2089 ◽  
Author(s):  
EL Ghisalberti ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Diffraction Study ◽  
Structural Study ◽  
Spectroscopic Studies ◽  
Diels Alder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Naturally Occurring ◽  
Chemical Evidence ◽  
Alder Adduct

The structure of the compound obtained on heating the naturally occurring clerodane furanoditerpene (1) had been formulated as (2) on the basis of spectroscopic studies. A single-crystal X-ray diffraction study on the dihydro derivative of (2) has confirmed this and provides support for the stereochemistry previously assigned to (1) on the basis of chemical evidence.

Einfache Synthese von 2,2-Diethoxy-2,5-dihydrofuranen, 2(5 H)Furanonen und 2-Ethoxy-furanen.Kristall-und Molekülstruktur eines Barrelenon Diels-Aider Produktes [1] / Convenient Synthesis of 2,2-Diethoxy-2,5-dihydrofurans, 2(5 H)Furanones and 2-Ethoxyfurans.Crystal and Molecular Structure of a Barrelenone Diels-Alder Product [1]

1994 ◽  
Vol 49 (3) ◽  
pp. 389-406 ◽  
Author(s):  
Rolf W. Saalfrank ◽  
Wieland Hafner ◽  
Joachim Markmann ◽  
Andreas Welch ◽  
Karl Peters ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Maleic Anhydride ◽  
Structure Analysis ◽  
Diels Alder ◽  
Dimethyl Acetylenedicarboxylate ◽  
Reaction Conditions ◽  
X Ray ◽  
Convenient Synthesis

AbstractReaction of 1,2-hydroxyketones 5 with (2,2-diethoxyvinylidene)triphenylphosphorane (2) or (2,2-diethoxyvinyl)triphenylphosphonium tetrafluoroborates 6 yields the 2,2-diethoxy- 2.5-dihydrofurans 9. Depending on the reaction conditions used, the orthoesters 9 can be hydrolized to give 2(5 H)furanones 10 and 2-ethoxyfurans 11, respectively. 4,5-Dimethyl- 5.6-dihydro-2-pyranone (20) and 8-methoxycoumarin (23) are prepared, starting from (2,2-diethoxyvinyl)triphenylphosphonium tetrafluoroborate (6 a) and 1-hydroxy-2-methyl- 3-butanone (16) or 2-hydroxy-3-methoxy-benzaldehyde (21). The 2-ethoxyfuranes 11 readily undergo Diels-Alder reactions with 2-chloracrylonitrile (24), maleic anhydride (26), N-phenyl-1,2,4-triazoline-3,5-dione (28) and dimethyl acetylenedicarboxylate (30) to give the corresponding Diels-Alder products 25, 27, 29 and 31, respectively. Contrary to 2-ethoxyfuran 11b , 11a reacts with two equivalents of acetylene 30, to yield barrelenone 34. The structure of 34 unequivocally is established by X-ray structure analysis.

Corroles in 1,3-dipolar cycloaddition reactions

2009 ◽  
Vol 13 (03) ◽  
pp. 358-368 ◽  
Author(s):  
Luís S. H. P. Vale ◽  
Joana F. B. Barata ◽  
Carla I. M. Santos ◽  
Maria G. P. M. S. Neves ◽  
Maria A. F. Faustino ◽  
...  
Keyword(s):  
Single Crystal ◽  
Diffraction Analysis ◽  
Dimethyl Fumarate ◽  
Azomethine Ylide ◽  
Dipolar Cycloaddition ◽  
Dimethyl Acetylenedicarboxylate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dipolar Cycloadditions ◽  
Pyridine Complex

The azomethine ylide generated from the reaction of a corrole-3-carbaldehyde and N-methylglycine was trapped with dimethyl fumarate, dimethyl acetylenedicarboxylate and fullerene C60 in 1,3-dipolar cycloadditions. A similar azomethine ylide generated from a corrole-2-carbaldehyde was trapped with 1,4-naphthoquinone, yielding the expected dehydrogenated 1,3-dipolar cycloadduct and a quinone-fused corrole derivative. A detailed synchrotron single-crystal X-ray diffraction analysis of the gallium(III)(pyridine) complex of 5,10,15-tris(pentafluorophenyl)corrole-3-carbaldehyde is also presented.

Spiro fused β-lactam cyclopropenes

1992 ◽  
Vol 70 (12) ◽  
pp. 2967-2971 ◽  
Author(s):  
Michel Zoghbi ◽  
John Warkentin
Keyword(s):  
Molecular Structure ◽  
Single Crystal ◽  
Strain Energy ◽  
High Strain ◽  
Dimethyl Acetylenedicarboxylate ◽  
X Ray Diffraction ◽  
Cyclopropene Ring ◽  
X Ray ◽  
Lactam Ring ◽  
High Strain Energy

Δ3-1,3,4-Oxadiazolines (1) that share their C2 with C4 of a β-lactam ring in a spiro fusion were prepared. The structures were established through single crystal X-ray diffraction of 1a and by infrared, 1H, and 13C nuclear magnetic resonance spectroscopies. Thermolysis of 1 at 100 °C, in benzene containing dimethyl acetylenedicarboxylate, afforded spiro-fused β-lactam cyclopropene 12 in 33% yield. Similar thermolysis of 1b in the presence of ethyl phenylpropiolate gave spiro-fused β-lactam cyclopropene 13 (32%). The molecular structure of 12, determined by single crystal X-ray diffraction, has the two ester carbonyl carbons out of the plane of the cyclopropene ring by about 0.17 Ǻ, indicating substantial nonbonded steric interactions and suggesting unusually high strain energy. At 154.5 °C, 12 underwent isomerization to 19, presumably through a vinyl carbene intermediate.

scholarly journals Supramolecular Diversity of Oxabicyclo[2.2.2]octenes Formed between Substituted 2H-Pyran-2-ones and Vinyl-Moiety-Containing Dienophiles

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1714
Author(s):  
Krištof Kranjc ◽  
Amadej Juranovič ◽  
Marijan Kočevar ◽  
Franc Perdih
Keyword(s):  
Single Crystal ◽  
Room Temperature ◽  
Thermal Conditions ◽  
Diels Alder ◽  
X Ray Diffraction ◽  
Secondary Product ◽  
X Ray ◽  
Primary Products ◽  
Stereogenic Centers ◽  
Pressure Synthesis

In Diels–Alder reactions, 2H-pyran-2-ones as dienes can yield a large variety of cycloadducts with up to four contiguous carbon stereogenic centers. Some of the potentially most useful, however difficult to prepare due to their low thermal stability, are the primary CO2-containing oxabicyclo[2.2.2]octenes, which could be formed as eight distinctive isomers (two sets of regioisomers, each of these composed of four different stereoisomers). A high-pressure synthesis of such products was recently described in a few cases where vinyl-moiety-containing dienophiles were used as synthetic equivalents of acetylene. However, structures of the primary products have been so far only rarely investigated in detail. Herein, we present seven novel single-crystal X-ray diffraction structures of such cycloadducts of both stereoisomeric forms, i.e., endo and exo. Additionally, we present a single-crystal structure of a rare case of a cyclohexadiene system stable at room temperature, obtained as a secondary product upon the retro-hetero-Diels–Alder elimination of CO2 under thermal conditions (microwave irradiation), during this elimination the symmetry is increased and out of eight initially possible isomers of the reactant, this number in the product is decreased to four. In oxabicyclo[2.2.2]octene compounds, centrosymmetric hydrogen bonding was found to be the predominant motif and diverse supramolecular patterns were observed due to rich variety of C–H⋯O and C–H⋯π interactions.

Synthesis and Structure Analysis of N1,N4,3,6-Tetramethyl-N1,N4-Diphenyl-1,4-Dihydro-1,2,4,5-Tetrazine-1,4-Dicarboxamide

2012 ◽  
Vol 36 (3) ◽  
pp. 178-180 ◽  
Author(s):  
Guo-Wu Rao ◽  
Qi Li ◽  
Zhen-Guo Zhao
Keyword(s):  
Single Crystal ◽  
Structure Analysis ◽  
Title Compound ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
X Ray

N1, N4,3,6-Tetramethyl- N1, N4-diphenyl-1,4-dihydro-1,2,4,5-tetrazine-1,4-dicarboxamide was prepared from 3,6-dimethyl-1,6-dihydro-1,2,4,5-tetrazine, bis(trichloromethyl) carbonate and N-methylaniline. Its structure was confirmed by single-crystal X-ray diffraction. This reaction yields the title compound rather than N1, N2,3,6-tetramethyl- N1, N2-diphenyl-1,2-dihydro-1,2,4,5-tetrazine-1,2- dicarboxamide. The central tetrazine ring of the title compound exhibits a boat conformation and is therefore not homoaromatic.

scholarly journals X-ray structure of hexamethyl benzenehexacarboxylate, [C6(COOCH3)6]

1970 ◽  
Vol 34 (2) ◽  
pp. 197-200
Author(s):  
Shishir Ghosh ◽  
Md Kamal Hossain ◽  
Shariff E Kabir ◽  
Noorjahan Begum
Keyword(s):  
Thermal Treatment ◽  
Single Crystal ◽  
Diffraction Study ◽  
Key Words ◽  
Spectroscopic Data ◽  
Monoclinic Space Group ◽  
Dimethyl Acetylenedicarboxylate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Academy Of Sciences

The thermal treatment of [Ru2(CO)6(μ-η1,η2-C4H3O){μ-P(C4H3O)2}] 1 with dimethyl acetylenedicarboxylate (DMAD) at 110 °C leads to cyclotrimerization of DMAD. The cyclotrimerization product hexamethyl benzenehexacarboxylate, [C6(COOCH3)6] 2, was obtained in 37% yield and characterized by a combination of spectroscopic data and single crystal X-ray diffraction study. Compound 2 crystallizes in the monoclinic space group P1bar with a = 10.3002(12), b = 11.0371(13), c = 18.781(2) Å, α = 76.148(2), β = 87.390(2), γ = 74.001(2)°, Z = 4 and V = 1992.2(4) Å3. Key words: Cyclotrimerization; Dimethyl acetylenedicarboxylate; X-ray structure DOI: 10.3329/jbas.v34i2.6866Journal of Bangladesh Academy of Sciences, Vol. 34, No. 2, 197-200, 2010

Synthese und Röntgenstrukturanalyse von [Fe(η6-C6H4{1,3-(CH3)2})(η5 -C5(C6H5)5]+ [FeCl4]- / Synthesis and X-Ray Structure Analysis of [Fe(η6-C6H4{1 ,3 -(CH3)2})(η5-C5(C6H5)5]+ [FeCl4]-

1997 ◽  
Vol 52 (5) ◽  
pp. 573-576 ◽  
Author(s):  
Herbert Schumann ◽  
Alexander Lentz ◽  
Roman Weimann
Keyword(s):  
Single Crystal ◽  
Diffraction Analysis ◽  
Structure Analysis ◽  
Mass Spectra ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray

Abstract Fe[C5(C6H5)5](CO)2Br (1) reacts with m-xylene at 80°C followed by hydrolysis with diluted HCl in the presence of air, to give [Fe(η6-C6H4{1,3-(CH3)2})(775-C5(C6H5)5)]+[FeCl4]- (3). The 1H, 13CNMR and mass spectra as well as the single crystal X-ray diffraction analysis confirm the proposed sandwich cation structure. 3 crystallizes in the space group P 21/n with a = 984,0(1), b = 2201,0(7), c = 1684,9(2) pm, β = 91,94(1)° and V = 3647(1) x 10-30m3. The final refinement resulted in R = 0,054 for 2982 observed reflections with F0 ≥4σ (F0)

Synthesis and Structure Analysis of N1,N4-di-tert-Butyl-3,6-Dimethyl-1,4-Dihydro-1,2,4,5-Tetrazine-1,4-Dicarboxamide

2012 ◽  
Vol 36 (3) ◽  
pp. 172-174 ◽  
Author(s):  
Guo-Wu Rao ◽  
Jia-Bin Ni ◽  
Qi Li
Keyword(s):  
Single Crystal ◽  
Structure Analysis ◽  
Title Compound ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Tert Butyl

N1, N4-Di- tert-butyl-3,6-dimethyl-1,4-dihydro-1,2,4,5-tetrazine-1,4-dicarboxamide was prepared from 3,6-dimethyl-1,6-dihydro-1,2,4,5-tetrazine, and its structure was confirmed by single-crystal X-ray diffraction. This reaction yields the 1,4-dicarboxamide derivative rather than the 1,2-dicarboxamide derivative. The central six-member ring of the title compound has a boat conformation and therefore, is not homoaromatic.

Sign in / Sign up

Export Citation Format

Share Document