Structure elucidation, regioselective alkylation, and ring-opening of 2-phenyl-3H-pyridazino[6,1-b]quinazoline-3,10(5H)-dione

Dorottya Csányi, György Hajós, Géza Timári, Zsuzsanna Riedl, András Kotschy, Thomas Kappe, László Párkányi, Orsolya Egyed, Mária Kajtár-Peredy, Sándor Holly

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3 Citations (Scopus)


Structure elucidation of 2-phenyl-3H-pyridazino[6,1-b]quinazoline-3,10(5H)-dione (1) revealed that it exists in one of the four possible tautomeric structures (i.e. 1a). Although this tautomeric form has two different carbonyl groups, only one of these can be detected in the IR and Raman spectra. X-ray investigation led to the conclusion that this abnormal spectral behaviour is due to a special orientation of the molecules in the unit cell. Alkylation of 1 in the presence of a base in an organic solvent under anhydrous conditions afforded an O-alkyl derivative as the main product accompanied by a small amount of the 5-N-alkyl derivative, whereas under aqueous basic conditions a hydrolytic ring-opening took place to afford a new zwitterion as the main product.

Original languageEnglish
Pages (from-to)133-138
Number of pages6
JournalEuropean Journal of Organic Chemistry
Issue number1
Publication statusPublished - Jan 1 2002


  • Alkylations
  • Molecular electrostatic potential map
  • Ring-opening reaction
  • Site selectivity
  • Zwitterions

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry

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