Conformational studies of some N-acyl-t(3)-isopropyl-r(2),c(6)-bis-(2'-furyl)piperidin-4-ones

摘要

The high resolution 1H and 13C NMR spectra of four N-acyl-t(3)-isopropyl-r(2),c(6)-bis(2'-furyl)piperidin-4-ones 1-4 have been recorded at various temperatures and analysed.The spectra reveal the presence of two rotameric fonns (E and Z) in solution.1H-1H COSY spectra for 1-4 and 1H-13C COSY spectrum for 4 have been recorded to assist the assignment of the signals for the E and Z isomers of 1-4.Coupling constants predict an equilibrium mixture of boat form B1 and alternate chair form CA for 1-4.The effect of varying the substituents at nitrogen on the 1H and 13C chemical shifts have been analysed in detail.Mass spectra have also been recorded for 1-5.