Conformational analysis of some 5-substituted 5H-dibenzo[a,d]cycloheptenes

Abstract

Conformations and inversion barriers of 5H-dibenzo[a,d]cycloheptene (1a), 5-amino-5H-dibenzo[a,d]cycloheptene (1b), 5-chloro-5H-dibenzo[a,d]cycloheptene (1e), 5-hydroxy-5H-dibenzo[a,d]cycloheptene (1d), 5-methyl-5H-dibenzo[a,d]cycloheptene (1f), N-benzyl-5H-dibenzo[a,d]cyclohepten-5-imine (2) and N-(5H-dibenzo[a,d]cyclohepten-5-yl)benzylideneamine (1c) have been studied by means of dynamic nuclear magnetic resonance spectroscopy (DNMR) techniques, and comparison of the experimentally derived thermodynamic parameters was made with MM3, PM3 and ab initio calculated results. Attempts to determine the inversion barrier of 3-isopropyl-5H-dibenzo[a,d]cyclohepten-5-one (3) failed.