Nitrogen bridgehead compounds. Part 35. Structures of α-formyl-2,3-polymethylene-3,4-dihydroquinazolin-4-ones |
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| Authors: | ágnes Horváth István Hermecz Marianna Pongor-Csákvári Zoltán Mészáros József Kökösi Gábor Tóth áron Szöllósy |
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| Institution: | 1. CHINOIN Pharmaceutical and Chemical Works Ltd., Research Centre, H-1325 Budapest, P. O. Box 110, Budapest, Hungary;2. Pharmaceutical Chemical Institute of the Semmelweis Medical University, H-1088 Budapest, Puskin u. 7, Hungary;3. NMR Laboratory of the Institute for General and Analytical Chemistry, Technical University, H-1521 Budapest, P. O. Box 91, Hungary |
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| Abstract: | 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. |
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