A number of mono-, bi- and tricyclic 4-piperidones were prepared and their
NMR and IR spectra measured. The spectroscopic parameters show that the str
ain associated with these heterocycles decrease in the order tricyclic > bi
cyclic > monocyclic. It appears that in the case of the bicyclic system, pa
rt of the strain is relieved by one of its six-membered rings assuming a bo
at form and by flattening whereas in the tricyclic system the strain cannot
be relieved to a significant extent. Copyright (C) 2001 John Wiley & Sons,
Ltd.