Transannular Interactions in Difunctional Medium Rings. 1. n/? Interactions in Cyclic Amino Ketones and Aminoalkenes Studied by Photoelectron Spectroscopy

Article abstract of DOI:10.1021/jo00355a004

The He I photoelectron spectra of the cyclic and bicyclic amino ketones 1-4 and aminoalkenes 5-8 have been recorded and interpreted with respect to transannular interactions of the functional groups.The interactions have been determined by comparing the spectra of 1-8 with those of the monofunctional compounds 9-20.For 1-4 the n_O ionization can be considered as an indicator of transannular interaction.For 5-8 the amount of interaction is measured by the shifts of the n_N and the ?_CC orbitals.The results indicate considerable n/? interactions in the eight-membered rings of 2 and 6.Of the compounds with a ten-membered ring, there is only interaction in amino ketone 3, while it is virtually absent in aminoalkene 7.Conformations are proposed to account for these findings.