Synthesis of a series of cyclic 2,4-dienones and evaluation of their Diels–Alder reactivity with maleic anhydride

• Published in: Journal of the Iranian Chemical Society 2022-06, Vol.19 (6), p.2255-2262
• Main Authors: Abaee, M. Saeed, Pirouz, Maryam, Mohammadi, Mohaddeseh, Mojtahedi, Mohammad M., Notash, Behrouz
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Biochemistry; Chemical synthesis; Chemistry; Chemistry and Materials Science; Cycloaddition; Diels-Alder reactions; Dienes; Inorganic Chemistry; Maleic anhydride; NMR; Nuclear magnetic resonance; Organic Chemistry; Physical Chemistry; Short Communication; Stereochemistry; Toluene
• ISSN: 1735-207X; 1735-2428
• DOI: 10.1007/s13738-021-02462-y

Diels–Alder reactions of conjugated cyclic 2,4-dienones are a versatile tool for rapid and selective synthesis of multicyclic products. A new series of these dienes were synthesized in moderate yields for the first time, by using an aqueous NaOH solution within 2–3 h time periods. Then, the diene products were evaluated for their Diels–Alder reactivity under conventional thermal conditions. Cycloaddition of the parent diene with maleic anhydride, as an standard dienophile, solely produced a single phenyl substituted endo adduct of the hexahydronaphthofuran-trione structure. The optimum conditions were then successfully used for the synthesis of other derivatives of the target structure (within 10–16 h reflux in toluene). Spectroscopic studies, including 1 H NMR and 13 C NMR analyses, elucidated the structure and the endo stereochemistry of the products, in which the double bond has moved to the more stable endocyclic position. In addition, X-ray crystalography of one of the derivatives approved the suggested structure.