𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Inverse-electron-demand Diels–Alder reactions of 4-aryl-2-pyrones with electron-rich dienophiles

✍ Scribed by László Balázs; István Kádas; László Tõke

Publisher
Elsevier Science
Year
2000
Tongue
French
Weight
120 KB
Volume
41
Category
Article
ISSN
0040-4039

No coin nor oath required. For personal study only.

✦ Synopsis

The Diels-Alder reaction of 4-aryl-pyrones with electron-rich dienophiles afforded substituted biaryl derivatives in most cases. At the minimal temperatures necessary for a measurable conversion of the starting pyrones, the bicyclic lactones, the primary products of the condensation, underwent cycloreversion by extruding carbon dioxide and then aromatised through further eliminations. In the case of the more active 4-aryl-6-chloro-pyrone, a formal substitution was observed instead of the expected cycloaddition with an active dienophile, while in its reaction with a Schiff-base the primary product of the cycloaddition was trapped through the formation of a new tetrahydropyridine derivative.

📜 SIMILAR VOLUMES

Dienophilicity of Imidazole in Inverse E
Dienophilicity of Imidazole in Inverse Electron Demand Diels-Alder Reactions; Intermolecular Reactions with 1,2,4-Triazines.
✍ Zhaokui Wan; John K Snyder 📂 Article 📅 1997 🏛 Elsevier Science 🌐 French ⚖ 582 KB

Intermolecular cycloadditions between trialkyl 1,2,4-triazine-4,5,6-tricarboxyIatesand protected2-aminoimidazolegave IH-imidazo[4,5-c]pyridines (3-deazapurines)andthe rearranged3Hpyrido[3,2-d]pyrimid-4-ones (8-deazapteridines). No cycloadditions wereobservedwithimidazoleand2phenylimidazole.Q 1997Els

Dienophilicity of Imidazole in Inverse E
Dienophilicity of Imidazole in Inverse Electron Demand Diels-Alder Reactions; Intramolecular Reactions with 1,2,4-Triazines.
✍ Christopher E. Neipp; Peter B. Ranslow; Zhaokui Wan; John K. Snyder 📂 Article 📅 1997 🏛 Elsevier Science 🌐 French ⚖ 513 KB

Imidazole and 2-phenylimidazoleundergo intramolecularcycloadditions with 1,2,4triazines tethered betweenan imidazolenitrogenand the triazinylC3 position with a trimethylene chainto producetetrahydro-l,5-naphthyridines followingloss of N2 and a nitrile.