Pyrimidines carrying a dienophilic side-chain at the 2 or 5 position undergo intramolecular Diels-Alder reactions to give heterocyclic annelated pyridines. Inverse electron demand Diels-Alder reactions of heterocyclic azadienes with electron-rich dienophiles are well documented'. Recently, the intra
Intramolecular Diels-Alder reactions of pyrimidines: Synthesis of tricyclic annelated pyridines.
โ Scribed by W.A.W. Stolle; A.T.M. Marcelis; A. Koetsier; H.C. van der Plas
- Book ID
- 108372250
- Publisher
- Elsevier Science
- Year
- 1989
- Tongue
- French
- Weight
- 554 KB
- Volume
- 45
- Category
- Article
- ISSN
- 0040-4020
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Quaternization of alkynyl substituted pyrazines with triethyloxonium tetrafluoroborate in dichloromethane occurs exclusively at N-4 yielding 3-alkynyl-lethylpyrazinium salts, as shown by the 13C NMR data. Protonation of the same pyrazines with trifluoroacetic acid also occurs at N-4. The quaternary