The stereochemistry and regiochemistry of the Diels–Alder reactions of 6-acetoxy-2,6-dimethyl-2,4-cyclohexadienone

1981 ◽  
Vol 59 (16) ◽  
pp. 2510-2517 ◽  
Author(s):  
Hillar Auksi ◽  
Peter Yates
Keyword(s):  
Carboxylic Acid ◽  
Maleic Anhydride ◽  
Dicarboxylic Acid ◽  
Van Der Waals ◽  
Closed Shell ◽  
Diels Alder ◽  
Acid Anhydride ◽  
Propiolic Acid ◽  
High Stereoselectivity

6-Acetoxy-2,6-dimethyl-2,4-cyclohexadienone (1) and maleic anhydride in boiling benzene give a single adduct, exo-5-acetoxy-l,5-dimethyl-6-oxobicyclo[2.2.2]oct-7-ene-endo-2,3-dicarboxylic acid anhydride (2). With propiolic acid 1 gives exo-5-hydroxy-l,5-dimethyl-6-oxobicyclo[2.2.2]octa-2,7-diene-2-carboxylic acid (15). The high stereoselectivity and regioselectivity of these reactions is interpretable in terms of orbital overlap, closed-shell repulsion, steric, and van der Waals – London effects.

Annelated furans. VI. Diels-Alder addition to 3-Methoxy-2-vinylbenzofurans

1971 ◽  
Vol 24 (9) ◽  
pp. 1883 ◽  
Author(s):  
JD Brewer ◽  
WJ Davidson ◽  
JA Elix ◽  
RA Leppik
Keyword(s):  
Maleic Anhydride ◽  
Dicarboxylic Acid ◽  
Diels Alder ◽  
Acid Anhydride ◽  
Direct Route

The Diels-Alder addition of 3-methoxy-2-vinylbenzofurans to acetylenic dienophiles has been shown to be accompanied by elimination of methanol, thus affording a direct route to polyfunctional dibenzofurans. Ethylenic dienophiles also reacted but the nature of the product varied with the dienophile: thus tetra-cyanoethylene and 2- isopropenyl-3-methoxybenzofuran (17) gave the simple 1 : 1 adduct, 1,1,2,2-tetracyano-11-methoxy-4-methyl-1,2,3,11-tetrahydrodibenzofuran (26), while addition of maleic anhydride to (17) was accompanied by elimination of methanol to form the 1,2-dihydrodibenzofuran, 4-methyl- 1,2-dihydrodibenzofuran-1,2-dicarboxylic acid anhydride (27). ��� The addition of p-benzoquinone and 1,4-naphthaquinone to (17) gave the polycyclic quinones, 6-methyl-1,4-dioxo-1,4- dihydrobenzo[b]naphtho[1,2-d]furan (28) and 7-methyl-5,13-dioxo-5,13- dihydrobenzo[b]anthra[1,2-d]furan (29) respectively. ��� The methylation of enolic 3-hydroxybenzofurans has also been studied.

Reactions of phthalans with dienophiles. II. Synthesis of naphthalenes and dihydronaphthalenes by reaction of ethyl maleate and maleic anhydride with 1,1-diethoxyphthalan

1980 ◽  
Vol 58 (23) ◽  
pp. 2580-2583 ◽  
Author(s):  
Luis Contreras ◽  
David B. MacLean
Keyword(s):  
Maleic Anhydride ◽  
Dicarboxylic Acid ◽  
Atmospheric Pressure ◽  
Acid Anhydride ◽  
Diethyl Maleate ◽  
Insight Into ◽  
Mechanism Of The Reaction

The reactions of 1,1-diethoxyphthalan with diethyl maleate and with maleic anhydride have been studied. The reaction with diethyl maleate in a sealed tube gave a mixture of diethyl 1-hydroxynaphthalene-2,3-dicarboxylate and its O-ethyl derivative. The same reactants at atmospheric pressure gave the ethoxy ester above along with a mixture of isomeric diethyl 1,2-dihydro-1-hydroxy-4-ethoxynaphthalene-2,3-dicarboxylates. The reaction with maleic anhydride gave only diethyl-1-ethoxynaphthalene-2,3-dicarboxylic acid anhydride. These reactions provide further insight into the mechanism of the reaction of phthalans with dienophiles.

scholarly journals The Role of Supramolecular Intermediates in the Potential Energy Surface of the Diels-Alder Reaction

2017 ◽  
Vol 57 (4) ◽  
Author(s):  
Karla Ramírez-Gualito ◽  
Néstor López-Mora ◽  
Hugo A. Jiménez-Vázquez ◽  
Joaquín Tamariz ◽  
Gabriel Cuevas
Keyword(s):  
Maleic Anhydride ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Energy Surface ◽  
Van Der Waals ◽  
Cycloaddition Reaction ◽  
Alder Reaction ◽  
Diels Alder ◽  
Electrostatic Phenomena

The potential energy surface of four stereoselective Diels-Alder reactions was studied, namely: cyclopentadiene-maleic anhydride, furan-maleic anhydride, the dimerization of cyclopentadiene, and cyclopentadiene-cyclopropene. For completeness, we also studied the reaction between ethylene and 2-hydroxy-6-methyl-1,4-benzoquinone, a [5+2] cycloaddition reaction. For all cases at least a stationary state of supramolecular nature a van der Waals complex, was determined. These stationary states are complexes formed by the interaction between the reagents, minima located in the paths between the non-interacting molecules and the transition states. The existence of these complexes makes it necessary to reconsider the role of Secondary Orbital Interactions in the selectivity of these reactions. As it is the case with other complexes, the stability of these supramolecular intermediates depends on electrostatic phenomena such as dispersion forces. The observation of [5+2] intramolecular complexes in solution is important since up to now, this kind of van der Waals complexes had only been described in the gas phase.

Annelated furans. XV. The autoxidation of tetrahydrodibenzofurans

1975 ◽  
Vol 28 (5) ◽  
pp. 1059 ◽  
Author(s):  
JD Brewer ◽  
JA Elix
Keyword(s):  
Carboxylic Acid ◽  
Dicarboxylic Acid ◽  
Ground State ◽  
Benzene Solution ◽  
Chloroform Solution ◽  
Heterocyclic Ring ◽  
Acid Anhydride ◽  
Alternative Route ◽  
State Process ◽  
Aromatic Species

The autoxidation of N-phenyl-1,2,3,9b-tetrahydrodibenzofuran-1,2-dicarboximide and the corresponding 4-methyl and 4-phenyl derivatives, in benzene solution, produced a mixture of the respective stereoisomeric 4-hydroperoxy-1,2,3,4-tetrahydrodibenzofuranisn each case. This reaction was shown to be a ground state process and resulted in the rearrangement of the 1,2,3,9b-tetrahydrodibenzofuran system to the thermodynamically more stable 1,2,3,4-tetrahydrodibenzofuran moiety. The introduction of a 4-acetoxy or 3-methoxycarbonyl substituent into the 1,2,3,Yb-tetrahydrodibenzofuran system appeared to facilitate the autoxidation process, and the initial N-phenyl-1,2,3,9b-tetrahydrodibenzofuran- 1,2-dicarboximides could not be isolated in these instances. Some reactions of c-4- and t-4-hydroperoxy-4-methyl-N-phenyl-1,2,3,4-tetrahydrodibenzofuran-r-1,c-2-dicarboximide have been investigated. These hydroperoxides decomposed on warming in chloroform solution to produce 4-methyl-N-phenyl-1,2-dihydrodibenzofuran-1,2-dicarboximide and 4-methyl-N-phenyldibenzofuran-1,2-dicarboximide In addition to the latter product, treatment of the mixture of hydroperoxides with p-toluenesulphonic acid in chloroform solution resulted in cleavage of the heterocyclic ring to give 5-ethoxy-3-(2'-hydroxyphenyl)-5-methyl-4-oxo-N-phenylcyclohex- 2-ene-1,2-dicarboximide (44). The autoxidation of 4-methyl-1,2,3,9b-tetrahydrodibenzofuran-1,2-dicarboxylic acid anhydride (48) proceeded by an alternative route and gave a novel peroxylactone, 6-methyl-3-oxo-3,3a,4,5- tetrahydrobenzofuro[2,3-h]-1,2-benzodioxoe-4-carboxylic acid (50), in addition to the fully aromatic species, 4-methyldibenzofuran-1,2-dicarboxylic acid anhydride (59) The synthesis and autoxidation of 1-acetyl-4-methyl-1,2,3,9b-tetrahydrodibenzofurawn as also studied. Finally the reaction of N-phenylmaleimide with 2-(3'-benzofuranyl)but-1-ene (72) was shown to give 1-ethyl-N-phenyl-2,3,4,4a-tetrahydrodibenzofuran-3,4-dicarboximide (73 ). Autoxidation of the latter compound proceeded with rearrangement to give r-1-ethyl-1-hydroperoxy-N-phenyl-1,2,3,4- tetrahydrodibenzofuran-t-3,t-4-dicarboximide (74).

Isolation and identification of by-products of gas phase catalytic oxidation of anthracene to 9,10-anthraquinone

1983 ◽  
Vol 48 (1) ◽  
pp. 112-122 ◽  
Author(s):  
Ivan Chvátal ◽  
Jan Vymětal ◽  
Jaroslav Pecha ◽  
Vilím Šimánek ◽  
Ladislav Dolejš ◽  
...  
Keyword(s):  
Maleic Anhydride ◽  
Catalytic Oxidation ◽  
Gas Phase ◽  
Phthalic Anhydride ◽  
Maleic Acid ◽  
Phthalic Acid ◽  
Diels Alder ◽  
Acid Anhydride ◽  
Isolation And Identification ◽  
By Products

A total of 29 associate components were identified in technical 9,10-anthraquinone. The product contained all the prominent impurities present in the starting anthracene except for 9,10-dihydroanthracene and fluorene. 9-(9'-Anthryl)-carbazole and Diels-Alder type adducts of anthracene with maleic anhydride and with maleinimide were also detected. The isolated and identified by-products of oxidation of anthracene were 1,4-anthraquinone, 4,4'-dioxo-1,1'-bianthrylidene, 4,10'-dioxo-1,9'-bianthrylidene, 1-(4'-oxy-1'-naphthylidene)-4-oxyanthracene, 2,3-naphthalenedicarboxylic acid and anhydride, and 5,7,12,14-tetrahydro-5,14;7,12-di(o-benzeno)pentacene-6,13-dione. Of the compounds formed by oxidation of the anthracene impurities, isolated and identified were dibenzo[b,d]pyrone, xanthone, 1,8-naphthalenedicarboxylic acid anhydride,9-fluorenone, and naphthol[2,3-b]thiophene-4,9-dione. As products of a deeper oxidation of the starting compounds, phthalic anhydride, maleic anhydride, maleinimide, phthalic acid, and maleic acid were found. Four additional components whose structure could not be determined were also isolated. The pathway of the anthracene oxidation is suggested.

Angucyclinones Related to Ochromycinone. IV. The Structures and Reactions of Unusual Diels-Alder Adducts Formed from Maleic Anhydride and Racemic 5,5-Dimethyl-3-vinylcyclohex-2-en-1-ol

2000 ◽  
Vol 53 (5) ◽  
pp. 403 ◽  
Author(s):  
Craig Brinkworth ◽  
Tomas Rozek ◽  
John H. Bowie ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Carboxylic Acid ◽  
Maleic Anhydride ◽  
Anticancer Activity ◽  
Alder Reaction ◽  
Major Product ◽  
Diels Alder ◽  
Epoxide Ring ◽  
X Ray ◽  
Osmium Tetraoxide ◽  
Diels Alder Reaction

The Diels–Alder reaction between maleic anhydride and racemic 5,5-dimethyl-3-vinylcyclohex-2-en-1-ol gives two racemic diastereomers, the major product (2a,S,3R,8aS,8bR)-7,7-dimethyl-2-oxo-2a,3,4,6,7,8,8a,8b-octahydro-2H-benzo[cd]isobenzofuran-3-carboxylic acid (63% yield), and the minor product (2aR,3S,8aS,8bS)-7,7-dimethyl-2-oxo-2a,3,4,6,7,8,8a,8b-octahydro-2H-benzo[cd]isobenzofuran-3-carboxylic acid (9%). Epoxidation of the major product gives racemic (1aS,3R,3aS,5aR,8aS,8bR)-7,7-dimethyl-4 oxoperhydro-benzo[cd]oxireno[2,3-e]isobenzofuran-3-carboxylic acid in 81% yield, while opening of the epoxide ring gave the trans diol (2aS,3R,5S,5aR,8aR,8bR)-5,5a-dihydroxy-7,7-dimethyl-2-oxoperhydrobenzo[cd]isobenzofuran-3-carboxylic acid in 58% yield. Treatment of the major Diels–Alder product with osmium tetraoxide gave the cis diol (2aS,3R,5S,5aR,8aS,8bR)-5,5a-dihydroxy-7,7-dimethyl-2-oxoperhydrobenzo[cd]isobenzofuran-3-carboxylic acid in 86% yield. The structures of four products were confirmed by X-ray and n.m.r. methods. None of the products exhibit anticancer activity.

Diels-Alder Reactions of Vinyl Derivatives of [1]Benzothieno[3,2-b]furan

1999 ◽  
Vol 64 (2) ◽  
pp. 389-407 ◽  
Author(s):  
Pavel Pihera ◽  
Hana Dvořáková ◽  
Jiří Svoboda
Keyword(s):  
Double Bond ◽  
Carboxylic Acid ◽  
Dicarboxylic Acid ◽  
Diels Alder ◽  
Dimethyl Acetylenedicarboxylate ◽  
Carboxylic Group ◽  
Methyl Propiolate ◽  
Vinyl Derivatives ◽  
Hydrolysis Of ◽  
Derivatives Of

2-Vinyl- (2) and 3-vinyl[1]benzothieno[3,2-b]furan (3) react with dimethyl acetylenedicarboxylate, methyl propiolate, maleic anhydride, or acrylonitrile endo-selectively as dienes to afford new [1]benzothieno[3,2-b][1]benzofuran derivatives 7-20. cis-Anhydrides 13 and 18 were transformed into dimethyl esters 21 and 22, respectively. It was shown that the base-catalyzed hydrolysis of 13 and 18 is accompanied by rearrangement of double bond in 13 and cis/trans isomerization of carboxylic group. Diesters 21 and 22, and nitriles 20 and 24 were aromatized by treatment with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. Selective monodecarboxylation of [1]benzothieno[3,2-b][1]benzofuran-8,9-dicarboxylic acid (26) and [1]benzothieno[3,2-b][1]benzofuran-6,7-dicarboxylic acid (27) afforded [1]benzothieno[3,2-b][1]benzofuran-8-carboxylic acid (28) and [1]benzothieno[3,2-b][1]benzofuran-7-carboxylic acid (29), respectively.

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