Model Compounds Related to Saquayamycin. Attempts to Oxygenate the A/B Ring Junction

2002 ◽  
Vol 55 (5) ◽  
pp. 343 ◽  
Author(s):  
M. A. Apponyi ◽  
J. H. Bowie ◽  
B. W. Skelton ◽  
A. H. White
Keyword(s):  
Double Bond ◽  
Maleic Anhydride ◽  
Good Yield ◽  
Ring Opening ◽  
Diels Alder ◽  
Aromatic System ◽  
Model Compounds ◽  
Similar Treatment ◽  
Ring Junction

The aim of this project was to attempt to find a method for introducing the cis-dihydroxyl substitution at the A/B-ring junction of model compounds related to the saquayamycins. The Diels-Alder reactions of maleic anhydride and bromomaleic anhydride with 5,5-dimethyl-3-vinylcyclohexa-1,2-dienyl acetate gave the two required endo-adducts in good yield, namely (octahydrobenzo[e]isobenzofuran-9-yl acetate (6) and (octahydrobenzo[e]isobenzofuran-9-yl acetate (9). Each of these was converted into the B-ring mono-epoxide, namely (H-benzo[e]oxireno-2,3-furan-1-yl acetate (7) and a mixture of two racemic diastereoisomers of 9a-bromo-3,3-dimethyl-7,9-dioxoperhydrobenzo[e]oxi- reno[2,3-f]isobenzofuran-1-yl acetate (12), respectively. It was then hoped to deprotonate both (7) and (12) at the 9a position in order to effect migration of the 8,9 double bond to the 9,9a position. Reaction of (7) with a mild base (pyridine) did not effect any reaction. Similar treatment of (12) did remove the 9a proton, but it also effected ring opening of the epoxide, followed by dehydration and dehydrobromination to give an excellent (but unwanted) yield of the aromatized system (±)-7,7-dimethyl-1,3-dioxo-1,3,5,7-tetrahydrobenzo (e]isobenzofuran-9-yl acetate. Dehydrobromination of (9), and deprotonation of the 9a position, similarly formed the aromatic system (e]isobenzofuran-9-yl acetate (11) in good yield.

scholarly journals Lead tetraacetate oxidation of the Diels-Alder adduct of 7-dehydrocholestryl acetate with maleic anhydride

2000 ◽  
Vol 65 (3) ◽  
pp. 147-156 ◽  
Author(s):  
Lidija Bondarenko-Gheorghiu ◽  
Ljubinka Lorenc ◽  
Mihailo Mihailovi]
Keyword(s):  
Double Bond ◽  
Maleic Anhydride ◽  
Total Yield ◽  
Diels Alder ◽  
Lead Tetraacetate ◽  
Starting Material ◽  
Large Excess ◽  
Pyridine Solution ◽  
Alder Adduct

The Diels-Alder adduct (3), obtained by cycloaddition of 7-dehydrocholesteryl acetate (1) and maleic anhydride (2), was heated at ca. 90?C with a large excess of lead tetraacetate in pyridine solution for 5h. Under these conditions, compound 3 underwent lactonization with the participation of the olefinic ?6-double bond to give two isomeric monolactone derivatives, 9 and 10 (in a total yield of ca. 6%), and the bislactone product 11 (in 11.5% yield). The starting material was recovered in 36% yield.

Structure of Ethylene Propylene Dicyclopentadiene Terpolymers

1966 ◽  
Vol 39 (4) ◽  
pp. 964-968
Author(s):  
W. Cooper ◽  
D. E. Eaves ◽  
M. E. Tunnicloffe ◽  
G. Vaughan
Keyword(s):  
Double Bond ◽  
Infrared Spectra ◽  
Ring Opening ◽  
Iodine Monochloride ◽  
Model Compounds ◽  
Ethylene Propylene

Abstract Terpolymers of ethylene, propylenc and C14-dicyclopentadiene have been compared with model compounds to determine the structure of combined termonomer units. Reactions with iodine monochloride, bromine and the infrared spectra of the terpolymers indicate that dicyclopentadiene polymerizes at the 9,10 double bond without ring-opening or disproportionation.

Reactions of N-3′-furylbenzamide with some dienophiles

1979 ◽  
Vol 57 (3) ◽  
pp. 314-317 ◽  
Author(s):  
John N. Bridson
Keyword(s):  
Double Bond ◽  
Maleic Anhydride ◽  
Methyl Acrylate ◽  
Diels Alder ◽  
First Case ◽  
Dimethyl Maleate ◽  
Related Compounds ◽  
Alder Adduct

N-3′-Furylbenzamide gives a conventional Diels–Alder adduct with maleic anhydride but with dimethyl maleate and methyl acrylate further reactions take place at the enamide grouping of the initially formed adducts. Compounds have been isolated in which molecules of an alcohol, used as solvent, or the starting furan have added to the double bond of the 1:1 adducts. In the first case unstable alkoxyamides are formed; in the second stable 2:1 adducts result from a novel uncatalysed addition to the double bond of the enamide. The stereochemistry of these and related compounds is discussed.

Preparation and transformations of allenic ketones and 3(2H)-furanones

1984 ◽  
Vol 62 (11) ◽  
pp. 2429-2434 ◽  
Author(s):  
Steven Wolff ◽  
William C. Agosta
Keyword(s):  
Double Bond ◽  
Carboxylic Acids ◽  
Good Yield ◽  
Osmium Tetroxide ◽  
Methyl Esters ◽  
Allene Oxide ◽  
Similar Treatment ◽  
Ruthenium Tetroxide ◽  
Swern Oxidation ◽  
Villiger Oxidation

Swern oxidation of allenic alcohols 7 and 10 gives the corresponding ketones 3 and 12. Reaction of 3 with ruthenium tetroxide yields the stable acyl ketene 17 and the acyloxy α-diketone 20 as well as pivalil (4). Formation of 20 by way of the 3(2H)-furanone 22 is suggested, since oxidation of 3 and 12 with osmium tetroxide followed by dehydration provides the corresponding furanones 22 and 26 in good yield. Epoxidation of 3 furnishes some 20 as well as 27 and 29, the first stable keto allene oxide and bisepoxide, respectively. On thermolysis 27 rearranges to furanone 22. The double bond of 22 is cleaved by peracid to form 20; similar treatment of 31a, b leads to cleavage of the double bond accompanied by Baeyer–Villiger oxidation, with formation of the carboxylic acids corresponding to methyl esters 33a, b as the major products.

scholarly journals Reactions of Vinylcyclopropane and Bicyclopropyl Compounds With Maleic Anhydride

2019 ◽  
Vol 53 (4) ◽  
Author(s):  
C. K. Jankowski ◽  
A. Pelletier ◽  
Eduardo Díaz ◽  
Jacqueline M. R. Belanger ◽  
J.R. J. Paré ◽  
...  
Keyword(s):  
Maleic Anhydride ◽  
2D Nmr ◽  
Alder Reaction ◽  
Diels Alder ◽  
Model Compounds ◽  
Diels Alder Reaction ◽  
C6 Compounds

Vinylcyclopropane and bicyclopropyl C6 compounds are studied as diene precursors in the Diels-Alder reaction. Their rearrangement under different thermal and microwave conditions leads to specific isomeric hexa-, penta- or butadienes, condensed with maleic anhydride as a dienophile. Adduct stereochemistries were compared to those of previously-synthesized model compounds, and are fully characterized with 2D NMR and GC-MS spectroscopies. Some unsaturated terpenes bearing vinylcyclopropane moieties were also condensed, and their adduct structures assigned.

Configuration on the C=N double bond of monosubstituted amidines and amidoximes

1989 ◽  
Vol 54 (12) ◽  
pp. 3245-3252 ◽  
Author(s):  
Bernard Tinant ◽  
Janine Dupont-Fenfau ◽  
Jean-Paul Declercq ◽  
Jaroslav Podlaha ◽  
Otto Exner
Keyword(s):  
Double Bond ◽  
Nitrogen Atom ◽  
Steric Effects ◽  
Model Compounds ◽  
X Ray ◽  
Analogous Model

Configuration on the C=N double bond of amidines and amidoximes is controlled by steric effects on the second nitrogen atom but there is a difference in the case of N’-monosubstituted derivatives: amidines prefer E configuration (conformation around the C-N bond sp) and amidoximes Z configuration (conformation ap). This was confirmed by the X-ray structures of two analogous model compounds N,N’-dimethyl-4-nitrobenzamidine (monoclinic, P21c, a = 10.855(3), b = 11.043(3), c = 8.593(3) Å, β = 105.69(2)°, V = 991.8(5) Å3, Z = 4, Dx = 1.29 g cm-3, CuKα, λ = 1.5418 Å, μ = 7.91 cm-1, F(000) = 408, T = 291 K, R = 0.065 for 1 265 observed reflections) and N’-methyl-4-nitrobenzamidoxime (monoclinic, P21/a, a = 6.699(2), b = 24.178(9), c = 6.075(2) Å, β = 106.20(3)°, V = 944.9(6) Å3, Z = 4, Dx = 1.37 g cm-3, CuKα, λ = 1.5418 Å, μ =9.22 cm-1, F(000) = 408, T = 291 K, R = 0.079 for 1 278 observed reflections).

Reactions of 4-Pyrones with Azomethine Ylides as a Chemo­selective Method for the Construction of Multisubstituted Pyrano[2,3-c]pyrrolidines

Synthesis ◽  
2021 ◽  
Author(s):  
Dmitrii L. Obydennov ◽  
Vyacheslav D. Steben’kov ◽  
Konstantin L. Obydennov ◽  
Sergey A. Usachev ◽  
Vladimir S. Moshkin ◽  
...  
Keyword(s):  
Double Bond ◽  
Ring Opening ◽  
Azomethine Ylides ◽  
Azomethine Ylide ◽  
Dipolar Cycloaddition ◽  
Computational Studies ◽  
Carbon Double Bond ◽  
Reactivity Indexes ◽  
Reaction Proceeds

Abstract4-Pyrones bearing electron-donating and electron-withdrawing groups react with nonstabilized azomethine ylides to form pyrano[2,3-c]pyrrolidines in moderate to good yields. The reaction proceeds chemoselectively as a 1,3-dipolar cycloaddition of the azomethine ylide at the carbon–carbon double bond of the pyrone activated by the electron-withdrawing substituent. The reactivity of 4-pyrones toward azomethine ylides was rationalized by computational studies with the use of reactivity indexes. The pyrano[2,3-c]pyrrolidine moiety could be modified, for example by a ring-opening transformation under the action of hydrazine to provide pyrazolyl-substituted pyrrolidines.

Sign in / Sign up

Export Citation Format

Share Document