Furoic acid and derivatives as atypical dienes in Diels-Alder reactions

The furan Diels-Alder (DA) cycloaddition reaction has become an important tool in green chemistry, being central to the sustainable synthesis of many chemical building blocks. The restriction to electron-rich furans is a significant limitation of the scope of suitable dienes, in particular hampering...

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Bibliographic Details
Published in:Green chemistry : an international journal and green chemistry resource : GC 2021-08, Vol.23 (15), p.553-551
Main Authors: Cioc, R zvan C, Smak, Tom J, Crockatt, Marc, van der Waal, Jan C, Bruijnincx, Pieter C. A
Format: Article
Language:English
Subjects:
Acids
Adducts
Amides
Chemical synthesis
Chemistry
Conversion
Couplings
Cycloaddition
Diels-Alder reactions
Dienes
Esters
Furans
Furoic acid
Green chemistry
Pesticides
Salts
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Summary:The furan Diels-Alder (DA) cycloaddition reaction has become an important tool in green chemistry, being central to the sustainable synthesis of many chemical building blocks. The restriction to electron-rich furans is a significant limitation of the scope of suitable dienes, in particular hampering the use of the furans most readily obtained from biomass, furfurals and their oxidized variants, furoic acids. Herein, it is shown that despite their electron-withdrawing substituents, 2-furoic acids and derivatives (esters, amides) are in fact reactive dienes in Diels-Alder couplings with maleimide dienophiles. The reactions benefit from a substantial rate-enhancement when water is used as solvent, and from activation of the 2-furoic acids by conversion to the corresponding carboxylate salts. This approach enables Diels-Alder reactions to be performed under very mild conditions, even with highly unreactive dienes such as 2,5-furandicarboxylic acid. The obtained DA adducts of furoic acids are shown to be versatile synthons in the conversion to various saturated and aromatic carbocyclic products. Bio-derived furoic acids and their derivatives are unexpectedly reactive dienes in aqueous Diels-Alder cycloadditions with maleimides.
ISSN:1463-9262
1463-9270
1463-9262
DOI:10.1039/d1gc01535d