4-Aryl-3-substituted Furans

1994 ◽  
Vol 59 (12) ◽  
pp. 2721-2726 ◽  
Author(s):  
Jarmila Štetinová ◽  
Ján Leško ◽  
Miloslava Dandárová ◽  
Rudolf Kada ◽  
Roman Koreň
Keyword(s):  
Thermal Decomposition ◽  
Triple Bond ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Substituted Furans

4-Aryl-3-substituted furans IIIa - IIId were prepared by Diels Alder reaction of 4-phenyloxazole (I) with compounds IIa - IId, containing an activated triple bond, and subsequent thermal decomposition of the cycloadduct.

A synthesis and some reactions of 7-Oxabicyclo[2.2.1]heptan-2-one

1983 ◽  
Vol 36 (12) ◽  
pp. 2473 ◽  
Author(s):  
J Moursounidis ◽  
D Wege
Keyword(s):  
Thermal Decomposition ◽  
Alder Reaction ◽  
Diels Alder ◽  
Acid Mixture ◽  
Diels Alder Reaction ◽  
Reaction Proceeds ◽  
Atom Migration ◽  
Acyl Azide ◽  
Mild Hydrolysis ◽  
Hydrolysis Of

Diels-Alder reaction between furan and α-chloroacrylonitrile gives a mixture of exo-2-chloro-and endo-2-chloro-7-oxabicyclo[2.2.1]hept-5-ene-2-carbonitrile (4) and (5). Mild hydrolysis affords the corresponding α-chloro acid mixture, from which the endo carboxylic acid may be removed through iodo lactone formation. Catalytic hydrogenation of (4) and (5) followed by hydrolysis, acyl azide formation, Curtius rearrangement, and hydrolysis of the resulting mixture of a-chloro isocyanates yields 7-oxabicyclo[2.2.l]heptan-2-one (1) in preparatively useful amounts. Reduction of (1) gives only endo alcohol, and Baeyer-Villiger reaction proceeds with exclusive bridgehead atom migration. Thermal decomposition of the sodium salt of the p-toluenesulfonylhydrazone of (1) affords 7-oxatricyclo[2.2.1 .02,6]heptane.

Diels−Alder Reaction of 2-Amino-Substituted Furans as a Method for Preparing Substituted Anilines

1997 ◽  
Vol 62 (12) ◽  
pp. 4088-4096 ◽  
Author(s):  
Albert Padwa ◽  
Martin Dimitroff ◽  
Alex G. Waterson ◽  
Tianhua Wu
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Substituted Anilines ◽  
Diels Alder Reaction ◽  
Substituted Furans

Dihydrothiophenes.10. The preparation and Diels–Alder reactions of some sulfur and phosphorus-substituted dienophiles and 2-aza-substituted 1,3-dienes

1984 ◽  
Vol 62 (11) ◽  
pp. 2089-2093 ◽  
Author(s):  
John M. McIntosh ◽  
Lilianna Z. Pillon
Keyword(s):  
Thermal Decomposition ◽  
Alder Reaction ◽  
Conjugated Dienes ◽  
Diels Alder ◽  
Diels Alder Reaction

The use of 3-carboxylated 2,5-dihydrothiophenes as the dienophilic component of the Diels–Alder reaction has been investigated. The yields are generally quite low. The formation of conjugated dienes that are aminated at an interior position of the conjugated chain by formation and thermal decomposition of 3-acetamido-2,5-dihydrothiophenes appears to be a viable route to these useful compounds. One example of the Diels–Alder reaction of 2-carboxylated diethyl vinylphosphonates is reported.

The synthesis, isomerization and stability of some enol-lactones

1982 ◽  
Vol 35 (9) ◽  
pp. 1903 ◽  
Author(s):  
IR Doyle ◽  
RA Massy-Westropp
Keyword(s):  
Thermal Decomposition ◽  
Wittig Reaction ◽  
Alder Reaction ◽  
Diels Alder ◽  
Kinetic Control ◽  
Relative Stabilities ◽  
Diels Alder Reaction ◽  
Wittig Reactions

The photoisomerization of enol-lactones is described. Thermal decomposition of (E) and (Z) ethyl 3-oxo-1,3,3aβ,4α,7α,7aβ-hexahydro-4,7-methanoisobenzofran-1-yideneacetates provides a good route to (E) and (Z) ethyl 5-oxo-2,5-dihydrofuran-2-ylideneacetates. Other examples of this retro-Diels-Alder reaction are reported. The relative stabilities of (E) and (Z) enol-lactones from the Wittig reaction between substituted succinic anhydrides and ethoxycarbonylmethylenetriphenylphosphorane have been determined. These Wittig reactions are under kinetic control.

scholarly journals Ring-closing metathesis of prochiral oxaenediynes to racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans

2020 ◽  
Vol 16 ◽  
pp. 2757-2768
Author(s):  
Viola Kolaříková ◽  
Markéta Rybáčková ◽  
Martin Svoboda ◽  
Jaroslav Kvíčala
Keyword(s):  
Triple Bond ◽  
Building Blocks ◽  
Ester Group ◽  
Alder Reaction ◽  
Diels Alder ◽  
Side Reactions ◽  
Enyne Metathesis ◽  
Ring Closing Metathesis ◽  
2Nd Generation ◽  
Diels Alder Reaction

The prochiral 4-(allyloxy)hepta-1,6-diynes, optionally modified in the positions 1 and 7 with an alkyl or ester group, undergo a chemoselective ring-closing enyne metathesis yielding racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans. Among the catalysts tested, Grubbs 1st generation precatalyst in the presence of ethene (Mori conditions) gave superior results compared to the more stable Grubbs or Hoveyda–Grubbs 2nd generation precatalysts. This is probably caused by a suppression of the subsequent side-reactions of the enyne metathesis product with ethene. On the other hand, the 2nd generation precatalysts gave better yields in the absence of ethene. The metathesis products, containing both a triple bond and a conjugated system, can be successfully orthogonally modified. For example, the metathesis product of 5-(allyloxy)nona-2,7-diyne reacted chemo- and stereoselectively in a Diels–Alder reaction with N-phenylmaleimide affording the tricyclic products as a mixture of two separable diastereoisomers, the configuration of which was estimated by DFT computations. The reported enediyne metathesis paves the way to the enantioselective enyne metathesis yielding chiral building blocks for compounds with potential biological activity, e.g., norsalvinorin or cacospongionolide B.

Influence of Lewis acids on the Diels–Alder reaction. II. Rearrangement of 1- and 1,4-substituted diethyl 7-oxabicyclo[2•2•1]2,5-heptadiene-2,3-dicarboxylate adducts to 4- and 4,6-substituted diethyl 3-hydroxyphthalates

1969 ◽  
Vol 47 (23) ◽  
pp. 4319-4326 ◽  
Author(s):  
A. W. McCulloch ◽  
B. Stanovnik ◽  
D. G. Smith ◽  
A. G. McInnes
Keyword(s):  
Lewis Acids ◽  
Room Temperature ◽  
Alder Reaction ◽  
Diels Alder ◽  
Substituted Phenols ◽  
Aryl Substituent ◽  
Diels Alder Reaction ◽  
Step Procedure ◽  
Direct Formation ◽  
Substituted Furans

Direct formation of 4- or 4,6-alkyl and aryl substituted diethyl 3-hydroxyphthalates from the correspondingly substituted Diels–Alder adducts of 2- or 2,5-substituted furans and diethyl acetylenedicarboxylate is promoted by AlCl3 in CH2Cl2 at room temperature. The first adduct of 2,5-diphenylfuran to be isolated has been obtained from the same reaction at −20°. The aromatic compounds can be obtained alternatively by treating the adducts with BF3 or H2SO4: where the adducts can be prepared by conventional means this two-step procedure has resulted in greatly improved yields. Adducts of furan and furfuryl alcohol are similarly converted to substituted phenols. HCl effected conversion only in the case of adducts carrying a bridgehead aryl substituent; in all other cases HCl added to the substituted double bond. The mechanism of the adduct rearrangement is discussed.

scholarly journals Ring closing metathesis of prochiral oxaenediynes to racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans

2020 ◽  
Author(s):  
Viola Kolaříková ◽  
Markéta Rybáčková ◽  
Martin Svoboda ◽  
Jaroslav Kvíčala
Keyword(s):  
Triple Bond ◽  
Building Blocks ◽  
Ester Group ◽  
Alder Reaction ◽  
Diels Alder ◽  
The Other ◽  
Side Reactions ◽  
Enyne Metathesis ◽  
Ring Closing Metathesis ◽  
Diels Alder Reaction

Prochiral 4-(allyloxy)hepta-1,6-diynes, optionally modified in the positions 1 and 7 with an alkyl or ester group, undergo chemoselective ring closing enyne metathesis yielding racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans. Among the catalysts tested, Grubbs 1st generation precatalyst in the presence of ethene (Mori conditions) gave superior results compared to more stable Grubbs or Hoveyda-Grubbs 2nd generation precatalysts. This is probably caused by suppression of subsequent side-reactions of the enyne metathesis product with ethene. On the other hand, 2nd generation precatalysts gave better yields in the absence of ethene. The metathesis products, containing both triple bond and conjugated system, can be successfully orthogonally modified. For example, metathesis product of 5-(allyloxy)nona-2,7-diyne reacted chemo- and stereoselectively by Diels-Alder reaction with N-phenylmaleimide affording tricyclic products as the mixture of two separable diastereoisomers, the configuration of which was estimated by DFT computations. The reported enediyne metathesis paves the way to enantioselective enyne metathesis yielding chiral building blocks for compounds with potential biological activity, e.g. norsalvinorin or cacospongionolide B.

IntraMolecular Diels–Alder Reactions of Vinylarenes and Alkynyl Arenes (the IMDAV Reaction)

Synthesis ◽  
2021 ◽  
Author(s):  
Fedor I. Zubkov ◽  
Gaddam Krishna ◽  
Dmitry G. Grudinin ◽  
Eugeniya V. Nikitina
Keyword(s):  
Multiple Bond ◽  
Alder Reaction ◽  
Diels Alder ◽  
Bioactive Molecules ◽  
Second Stage ◽  
Diels Alder Reaction ◽  
Naturally Occurring ◽  
Benzene Rings ◽  
Substituted Furans ◽  
Classical Mechanism

AbstractThis comprehensive review summarizes the published literature data concerning the intramolecular Diels–Alder reactions of vinylarenes (the IMDAV reaction) and alkynyl arenes from 1970 to 2019, and covers mainly intramolecular [4+2] cycloaddition reactions of vinyl- or acetylene-substituted furans, thiophenes, pyrroles, indoles, imidazoles, benzenes, and naphthalenes, in which the unsaturated substituent is linked directly to an arene moiety. The selected area of the Diels–Alder reaction differs from other forms of [4+2] cycloadditions due to the uniqueness of the diene fragment, which, along with an exocyclic multiple bond, includes the double bond of an aromatic or heteroaromatic nucleus in its system. Thus, during the formation of the [4+2] cycloaddition intermediate, the aromaticity of furan, thiophene and even benzene rings is broken, leading, as a rule, to the formation of heterocyclic structures rarely accessible by other methods, in contrast to the majority of intermolecular Diels–Alder reactions, with the highest degree of chemo-, regio-, and diastereoselectivity. Therefore, the IMDAV approach is often used for the synthesis of naturally occurring and bioactive molecules, which are also discussed in this review alongside other applications of this reaction. Whenever possible, we have tried to avoid examples of radical, photochemical, oxidative, precious-metal-complex-catalyzed cyclizations and other types of formal [4+2] cycloadditions, focusing on thermal Diels–Alder reactions in the first step, according to the classical mechanism. The second stage of the process, aromatization, is unique for many initial substrates, and hence considerable attention in this overview is given to the detailed description of the reaction mechanisms.1 Introduction2 IMDAV Reactions of Vinylfurans2.1 Alkenes as Internal Dienophiles2.2 Alkynes and Allenes as Internal Dienophiles3 IMDAV Reactions of Vinylthiophenes3.1 Alkenes as Internal Dienophiles3.2 Alkynes as Internal Dienophiles4 IMDAV Reactions of Vinylbenzothiophenes5 IMDAV Reactions of Vinylpyrroles6 IMDAV Reactions of Vinylindoles6.1 Alkenes as Internal Dienophiles6.2 Alkynes as Internal Dienophiles7 IMDAV Reactions of Styrenes and Vinylnaphthalenes7.1 Alkenes as Internal Dienophiles7.2 Alkynes as Internal Dienophiles7.3 Alkynes as Internal Dienophiles in Aryl Acetylenes (the Intramolecular Dehydro Diels–Alder Reaction)8 IMDAV Reactions of Vinylimidazoles, Vinylisoxazoles and Vinylpyridines9 Conclusion10 Abbreviations

Sign in / Sign up

Export Citation Format

Share Document