Diels−Alder Reactions of 1,3-Diphenylisobenzofuran with Ferrocenyl- and (η 6 -Phenyl)tricarbonylchromium Analogues of Chalcone as Well as Some Other Dienophiles
1996; American Chemical Society; Volume: 61; Issue: 10 Linguagem: Inglês
10.1021/jo9500850
ISSN1520-6904
AutoresMonika Prokešová, Eva Solčániová, Štefan Tomá, Kenneth W. Muir, A.A. Torabi, G. R. Knox,
Tópico(s)Synthesis and Reactions of Organic Compounds
ResumoThe Diels−Alder reactions of 1,3-diphenylisobenzofuran with acryloylferrocene (1), 4-ferrocenyl-3-buten-2-one (2), cinnamoylferrocene (3), 3-ferrocenyl-1-phenyl-2-propenone (4), chalcone (5), 1-((η6-phenyl)tricarbonylchromio)-3-phenyl-2-propenone (6), 1-phenyl-3-((η6-phenyl)tricarbonylchromio)-2-propenone (7), and (2-nitrovinyl)ferrocene (8) were examined under various conditions. The best results were achieved using SiO2 and a very acidic montmorillonite clay, KSF, as the catalyst, and the reactions were carried out without solvent. Reasonable to good yields of the Diels−Alder (D-A) products were isolated in most cases. X-ray structural studies showed that the adducts 13b and 13h, derived from the (E)-alkenes 2 and 8, have exo-acetyl or -nitro substituents and endo-ferrocenyl groups with respect to the bridging oxygen atom of the 7-oxabicycloheptane ring system. The product 13a from the monosubstituted enone 1 also has an exo-acyl (ferrocenylcarbonyl) group. Aluminum chloride was found to be a good catalyst for the reactions of 1,3-diphenylisobenzofuran with push-pull alkenes like 1, 2, 4, and 8. The unexpected products were derived from α-ferrocenyl carbocation attack on the diene, followed by electrophilic 2-substitution of the cyclopentadienyl ion ring, rather than D-A addition. The X-ray structure of the 8-oxabicyclooctane 12b, derived from 4, revealed an exo-ferroceno group and endo-phenacyl substituent.
Referência(s)