Stereochemical and electronic interaction studies of α-heterosubstituted acetone oximes

Article abstract of DOI:10.1016/0584-8539(95)01409-N

The free ν_C=N bands in the IR spectra of some α-heterosubstituted acetone oximes show the existence of only a monomeric form in chloroform solutions below 1E-2 M, while in carbon tetrachloride self-associated species are also present.The 1H and 13C NMR chemical shift data indicate the predominance of the E over the Z isomer.The Δν_C=N frequency shifts and molecular mechanics strongly suggest that the oximes are in the gauche conformation.X-ray diffraction data have shown that the single dimethylaminoacetone oxime isomer exists in the E configuration and gauche conformation.Non-additivity effects for the α-methylene carbon chemi cal shifts seem to indicate the occurence of a ?_C=N/?^*_C-x interaction besides the ?^*_C=N/?_C-X hyperconjugative interaction.