Nitrogen bridgehead compounds. Part 35. Structures of α‐formyl‐2,3‐polymethylene‐3,4‐dihydroquinazolin‐4‐ones

ágnes Horváth, István Hermecz, Marianna Pongor‐Csákvári, Zoltán Mészáros, József Kökösi, Gábor Tóth, áron Szöllósy

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The structures of the title compounds bearing a five‐, six‐ or seven‐membered A ring have been investigated by uv and 1H and 13C nmr spectroscopy. The imine‐enol‐enamine (I‐II‐III) tautomerism of these compounds depends greatly on the ring size. A significant solvent‐dependence is observed only for the five‐membered‐ring compounds 1 and 2, which in ethanolic solution exist predominantly in the imine form I, and in chloroform solution in the enol form II. The compounds with a six‐membered A ring, 3 and 4, are mainly in the enamine form III. On protonation, 3 and 4 change into the E and Z isomeric mixture of the enol tautomer II. The seven‐membered‐ring compound 5 is a mixture of the imine I and the enamine III tautomers.

Original languageEnglish
Pages (from-to)219-224
Number of pages6
JournalJournal of Heterocyclic Chemistry
Issue number1
Publication statusPublished - Jan 1 1984

ASJC Scopus subject areas

  • Organic Chemistry

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