Synthesis and spectroscopic studies of some polycyclic heterocyclic compounds

Abstract

Four tetrabenzo[b,d,h,j] [l,6] diazacyclododecines, series I, and their tetrahydro derivatives, series II, have been prepared [diagram].

1H N.m.r. spectra (220 MHz) and 13C n.m.r. spectra (22.63 MHz) of the compounds in both series were studied and assignments of the chemical shifts of most of the nuclei were made.

Temperature variable high resolution n.m.r. (220 MHz) was employed to study the behaviour of the methyl protons doublet in compounds (3) and (4) of series II, and the diastereotopic methylene protons in all compounds of 13 series II. It is concluded from these results and from the 13C n.m.r. spectra that compounds (1),(3) and (4) in series II must exist as two non-equivalent conformers.

The ultra-violet absorption spectra, in 95% ethanol, of the compounds in both series were determined. On the basis of these spectra and of the n.m.r. results it is concluded that the compounds in series I, must have the EE configuration.

Mass spectra of the four compounds in series II were measured by the Physico-Chemical Measurements Unit, Harwell. Fragmentation patterns are discussed in detail.

Lanthanide shift reagents, Eu(fod)₃ and Pr(fod)₃, were used extensively to help in the elucidation of the 1H n.m.r. spectra (60 MHz) of the compounds in both series. It was found that the mole ratio of the shift reagent/substrate in compounds of series I is 1:1, and 2:1 in compounds of series II. Chirality was observed in compounds (2), (3) and (4) of series I in the presence of large amounts of Eu(tfc) ₃ or Pr(tfc)₃ in CDCl₃ solutions. Compounds of series II are achiral under the conditions of the experiment.