Diels-Alder reactions with alkyl coumalates

A. K. Bahl, W. Kemp

Research output: Contribution to journalArticle

Abstract

Alkyl coumalates (methyl and ethyl 2-oxopyran-5-carboxylates) have been treated with a wide variety of dienophiles in Diels-Alder reactions. In all cases, extrusion of carbon dioxide occurred and multiple adducts were usually obtained; in one case a spontaneous loss of molecular hydrogen was observed. Thus methyl coumalate reacted with p-benzoquinone to give dimethyl anthraquinone-2,6-dicarboxylate (or the 2,7-analogue); with acetylenedicarboxylates, benzene-1,2,4-tricarboxylates were obtained; with benzyne, methyl naphthalene-2-carboxylate was formed. The adducts with maleic anhydride were 7-methoxycarbonylbicyclo[2,2,2]oct-7-ene-2,3;5,6-tetracarboxylic dianhydride and the 2-ethoxycarbonyl homologue. An analogous reaction with azodicarboxylate esters led (for example) to pentamethyl 2,3,5,6-tetra- azabicyclo[2,2,2]oct-7-ene-2,3,5,6,7-pentacarboxylate.

Original languageEnglish
Pages (from-to)2268-2271
Number of pages4
JournalJournal of the Chemical Society C: Organic
DOIs
Publication statusPublished - 1971

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Maleic Anhydrides
Anthraquinones
Benzene
Carbon Dioxide
Extrusion
Hydrogen
Esters
benzoquinone
benzyne
naphthalene

Cite this

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title = "Diels-Alder reactions with alkyl coumalates",
abstract = "Alkyl coumalates (methyl and ethyl 2-oxopyran-5-carboxylates) have been treated with a wide variety of dienophiles in Diels-Alder reactions. In all cases, extrusion of carbon dioxide occurred and multiple adducts were usually obtained; in one case a spontaneous loss of molecular hydrogen was observed. Thus methyl coumalate reacted with p-benzoquinone to give dimethyl anthraquinone-2,6-dicarboxylate (or the 2,7-analogue); with acetylenedicarboxylates, benzene-1,2,4-tricarboxylates were obtained; with benzyne, methyl naphthalene-2-carboxylate was formed. The adducts with maleic anhydride were 7-methoxycarbonylbicyclo[2,2,2]oct-7-ene-2,3;5,6-tetracarboxylic dianhydride and the 2-ethoxycarbonyl homologue. An analogous reaction with azodicarboxylate esters led (for example) to pentamethyl 2,3,5,6-tetra- azabicyclo[2,2,2]oct-7-ene-2,3,5,6,7-pentacarboxylate.",
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Diels-Alder reactions with alkyl coumalates. / Bahl, A. K.; Kemp, W.

In: Journal of the Chemical Society C: Organic, 1971, p. 2268-2271.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Diels-Alder reactions with alkyl coumalates

AU - Bahl, A. K.

AU - Kemp, W.

PY - 1971

Y1 - 1971

N2 - Alkyl coumalates (methyl and ethyl 2-oxopyran-5-carboxylates) have been treated with a wide variety of dienophiles in Diels-Alder reactions. In all cases, extrusion of carbon dioxide occurred and multiple adducts were usually obtained; in one case a spontaneous loss of molecular hydrogen was observed. Thus methyl coumalate reacted with p-benzoquinone to give dimethyl anthraquinone-2,6-dicarboxylate (or the 2,7-analogue); with acetylenedicarboxylates, benzene-1,2,4-tricarboxylates were obtained; with benzyne, methyl naphthalene-2-carboxylate was formed. The adducts with maleic anhydride were 7-methoxycarbonylbicyclo[2,2,2]oct-7-ene-2,3;5,6-tetracarboxylic dianhydride and the 2-ethoxycarbonyl homologue. An analogous reaction with azodicarboxylate esters led (for example) to pentamethyl 2,3,5,6-tetra- azabicyclo[2,2,2]oct-7-ene-2,3,5,6,7-pentacarboxylate.

AB - Alkyl coumalates (methyl and ethyl 2-oxopyran-5-carboxylates) have been treated with a wide variety of dienophiles in Diels-Alder reactions. In all cases, extrusion of carbon dioxide occurred and multiple adducts were usually obtained; in one case a spontaneous loss of molecular hydrogen was observed. Thus methyl coumalate reacted with p-benzoquinone to give dimethyl anthraquinone-2,6-dicarboxylate (or the 2,7-analogue); with acetylenedicarboxylates, benzene-1,2,4-tricarboxylates were obtained; with benzyne, methyl naphthalene-2-carboxylate was formed. The adducts with maleic anhydride were 7-methoxycarbonylbicyclo[2,2,2]oct-7-ene-2,3;5,6-tetracarboxylic dianhydride and the 2-ethoxycarbonyl homologue. An analogous reaction with azodicarboxylate esters led (for example) to pentamethyl 2,3,5,6-tetra- azabicyclo[2,2,2]oct-7-ene-2,3,5,6,7-pentacarboxylate.

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