Study of three-dimensional structures of benzoylpyridine oximes and their ethers by 1H and 13C NMR spectroscopy

The 1H and 13C NMR spectra of the E and Z isomers of 2-, 3-, and 4-benzoylpyridine oximes and their ethers were analyzed thoroughly, and the 1H-13C spin-spin coupling constants (SSCC) were determined. It was established that the magnitude of the γ effect for the quaternary carbon atoms in the E and Z isomers depends on the site of substitution in the pyridine ring. It was assumed that the intermolecular hydrogen bond is stronger in the E form than in the Z form. The existence of the Z isomer of 2-benzoylpyridine oxime in deuterochloroform with an intramolecular hydrogen bond was proved.