Ring[bond]chain tautomerism of 2-Aryl-substituted cis- and trans-decahydroquinazolines |
| |
Authors: | Lázár László Göblyös Anikó Martinek Tamás A Fülöp Ferenc |
| |
Institution: | Institute of Pharmaceutical Chemistry, University of Szeged, H-6701 Szeged, POB 121, Hungary. |
| |
Abstract: | In CDCl(3) at 300 K, 2-aryl-substituted cis- and trans-3-isopropyldecahydroquinazolines and trans-3-phenyldecahydroquinazolines proved to be three-component (r(1)bond]obond]r(2)) ringbond]chain tautomeric mixtures, whereas only ring-closed tautomers could be detected for the 3-methyl-substituted analogues. The proportions of the ring-chain tautomeric forms at equilibrium were strongly influenced by the N-substitutents and the cis-trans ring junction and could be described by the equation log K(X) = rho sigma(+) + log K(X=H). These are the first examples among 2-aryl-1,3-N,N-heterocycles of a three-component ring-chain tautomeric equilibrium characterized by a Hammett-type equation. The stabilities of the ring-closed forms of cis- and trans-2-aryldecahydroquinazolines and the corresponding 3,1-benzoxazines were found to increase in the following sequence of the heteroatom at position 3: NPh < N-i-Pr < O < NMe. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|