A~1,3 interaction and conformational preference in some N-acetyl-2-phenyl-trans-decahydroquinolin-4-ones

摘要

A~1,3 type strain is demonstrated directly by the nuclear magnetic resonance studies (~1H and ~13C NMR) on the N-acetyl derivatives of 2-phenyl-trans-decahydroquinolin-4-ones 5-8. In compounds 5-8 the bulky phenyl group is forced to assume axial orientation due to a severe A~1,3 interaction in equatiorial position. The ring torsional angles about C_(2)-C_(3) bond and Karplus constants have bene determined using DAERM method. The calculated torsional angles in the N-acetyl derivatives are significantly higher than that in the normal chair ocnformatin and thus confirm the nonchair (twist-boat) conformation of the heterocyclic ring with diaxial orientation of phenyl and alkyl groups in N-acetyl derivatives.