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.

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.

scholarly journals Insight on Solution Plasma in Aqueous Solution and Their Application in Modification of Chitin and Chitosan

2021 ◽  
Vol 22 (9) ◽  
pp. 4308
Author(s):  
Chayanaphat Chokradjaroen ◽  
Jiangqi Niu ◽  
Gasidit Panomsuwan ◽  
Nagahiro Saito
Keyword(s):  
Aqueous Solutions ◽  
Atmospheric Pressure ◽  
Scientific Progress ◽  
Biological Properties ◽  
Environmental Concerns ◽  
Plasma Process ◽  
Renewable Materials ◽  
Chemical Structures ◽  
Chitin And Chitosan ◽  
Insight Into

Sustainability and environmental concerns have persuaded researchers to explore renewable materials, such as nature-derived polysaccharides, and add value by changing chemical structures with the aim to possess specific properties, like biological properties. Meanwhile, finding methods and strategies that can lower hazardous chemicals, simplify production steps, reduce time consumption, and acquire high-purified products is an important task that requires attention. To break through these issues, electrical discharging in aqueous solutions at atmospheric pressure and room temperature, referred to as the “solution plasma process”, has been introduced as a novel process for modification of nature-derived polysaccharides like chitin and chitosan. This review reveals insight into the electrical discharge in aqueous solutions and scientific progress on their application in a modification of chitin and chitosan, including degradation and deacetylation. The influencing parameters in the plasma process are intensively explained in order to provide a guideline for the modification of not only chitin and chitosan but also other nature-derived polysaccharides, aiming to address economic aspects and environmental concerns.

Mechanistic Study on Gold(I)-Catalyzed Unsaturated Spiroketalization Reaction

2022 ◽  
Vol 19 ◽  
Author(s):  
Kamlesh Sharma
Keyword(s):  
Activation Barrier ◽  
Ring Formation ◽  
Hydroxyl Group ◽  
Mechanistic Study ◽  
Protecting Group ◽  
Wide Range ◽  
Oxocarbenium Ion ◽  
Metal Catalyzed ◽  
Insight Into ◽  
Mechanism Of The Reaction

Abstract: The mechanism of metal-catalyzed spiroketalization of propargyl acetonide is explored by employing DFT with the B3LYP/6-31+G(d) method. Acetonide is used as a regioselective regulator in the formation of monounsaturated spiroketal. The energies of transition states, intermediates, reactants and products are calculated to provide new insight into the mechanism of the reaction. The energetic features, validation of the observed trends in regioselectivity are conferred in terms of electronic indices via FMO analysis. The presence of acetonide facilitates a stepwise spiroketalization as it masks the competing nucleophile, and thus hydroxyl group present, exclusively acts as a nucleophile. The vinyl gold intermediate 3 is formed from 2 via activation barrier TS1. This is the first ring formation, which is 6-exo-dig cyclization. The intermediate 3 is converted into allenyl ether 4, which isomerizes to the intermediate oxocarbenium ion 5 via activation barrier TS2. The intermediate 5 cyclizes to 6 via TS3. This is the second ring formation. The intermediate 6 on protodeauration turns into 6,6-monounsaturated spiroketal 7. It is concluded that acetonide as a protecting group serves the purpose, and thus a wide range of spiroketals can be prepared, regioselectivity.

Hetero-Diels-Alder Reactions of Enaminothione with Electrophilic Olefins. Synthesis of 2-Furyl Substituted 2H-Thiopyrans

2002 ◽  
Vol 57 (6) ◽  
pp. 637-644 ◽  
Author(s):  
Krystyna Bogdanowicz-Szwed ◽  
Artur Budzowski
Keyword(s):  
Acetic Acid ◽  
Maleic Anhydride ◽  
Acetic Anhydride ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diethyl Maleate ◽  
Diels Alder Reaction

AbstractThe hetero-Diels-Alder reaction of 1-(2-furyl)-3-(dimethylamino)-2-propene-1-thione (diene) with maleic and fumaric acids, and β-nitrostyrenes yielded 3,4-dihydro-2H-thiopyran derivatives. Treatment of some of those cycloadducts with acetic acid caused elimination of dimethylamine yielding stable 2H-thiopyrans. Reaction of the diene with maleic anhydride furnished a cycloadduct which underwent spontaneous rearrangement to form an N,N-dimethylamide derivative. Cycloadditions of the diene to maleimide, N-phenylmaleimide, diethyl maleate, fumarate and butenolide, carried out in the presence of acetic anhydride,were followed by elimination of dimethylamine, afforded stable 2H-thiopyran derivatives.

THE ULTRAVIOLET ABSORPTION SPECTRA OF SOME CARBOXY DERIVATIVES OF NAPHTHALENE

1949 ◽  
Vol 27b (5) ◽  
pp. 437-461 ◽  
Author(s):  
Y. Hirshberg ◽  
R. Norman Jones
Keyword(s):  
Dicarboxylic Acid ◽  
Absorption Spectra ◽  
General Problem ◽  
Acid Anhydride ◽  
Ultraviolet Absorption ◽  
Dioxane Solution ◽  
Ethanolic Solution ◽  
Complex Molecules ◽  
Steric Inhibition Of Resonance ◽  
Derivatives Of

The ultraviolet absorption spectra of a variety of naphthalene compounds containing phenyl and carboxy substituents are described. The majority of the compounds contain either the naphthalene-1,2-dicarboxylic acid anhydride or the naphthalene-2,3-dicarboxylic acid anhydride ring systems. It is shown that in ethanolic solution the spectra of these anhydrides change over a period of a few hours. The spectra of the anhydrides in n-heptane or dioxane solution do not change on standing. The effects of the various substituents are discussed in terms of steric inhibition of resonance and of antagonistic and reinforcing actions of the substituents, dependent on the position of substitution. The significance of these data are considered in relation to the general problem of the interpretation of the ultraviolet absorption spectra of complex molecules.

Protoporphyrin Accumulation Induced by Peroxidizing Herbicides is Counteracted by Safeners

1994 ◽  
Vol 49 (11-12) ◽  
pp. 775-780 ◽  
Author(s):  
Peter Böger ◽  
Roswitha Miller
Keyword(s):  
Dicarboxylic Acid ◽  
Protoporphyrin Ix ◽  
Acid Anhydride ◽  
Mixed Function Oxidase ◽  
Maize Seedlings ◽  
Cyclic Imide ◽  
Protoporphyrinogen Oxidase ◽  
Naphthalic Anhydride ◽  
Target Enzyme

A number of safeners like naphthalene-1,8-dicarboxylic acid anhydride (naphthalic anhydride) or dichloroacetyl-hexahydro-3,3,8-α-trimethylpyrrolo-[1 ,2 α]-pyrimidine-6-(2H̲)-one (BAS 145138) drastically decreased the accumulation of protoporphyrin IX induced by a peroxidative cyclic imide (chlorophthalim, N-(4-chlorophenyl)-3,4,5,6-tetrahydrophthalimide), or p-nitrodiphenyl ether (acifluorfen methyl, 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoicmethylester). This effect was observed with etiolated maize and cress seedlings during a 16-h illumination period with these herbicides and 0.1 to 1 mᴍ safener present. The safeners did not affect the inhibition of protoporphyrinogen oxidase, the target enzyme of peroxidative herbicides. Mixed function oxidase inhibitors did not influence this safening effect. A microsome preparation from safener-treated maize seedlings did neither degrade protoporphyrin IX nor protoporphyrinogen IX.

Oxidation products of 2,3,6,7-tetramethoxy-9,10-dimethylphenanthrene

1970 ◽  
Vol 48 (11) ◽  
pp. 1785-1787 ◽  
Author(s):  
J. M. Edwards ◽  
Ulrich Weiss
Keyword(s):  
Dicarboxylic Acid ◽  
Oxidative Degradation ◽  
Acid Anhydride ◽  
Oxidation Products ◽  
Active Compounds ◽  
Temperature Oxidation ◽  
Ready Availability ◽  
Pharmacologically Active ◽  
Pharmacologically Active Compounds

Depending upon the conditions of solvent and temperature, oxidation of the readily accessible 2,3,6,7-tetramethoxy-9,10-dimethylphenanthrene (3) with Na2Cr2O7 gave 2,3,6,7-tetramethoxyphenanthrene-9,10-dicarboxylic acid anhydride (1), 2,2′-diacetyl-4,4′,5,5′-tetramethoxybiphenyl (4), or the new aldehyde 5. Compounds 1 and 4 have been obtained previously only by oxidative degradation of the alkaloid tylophorine (2); their ready availability may be of value for the synthesis of pharmacologically active compounds related to 2.

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