cis–trans Isomerism in monoalkylhydroxamic acids by 1H, 13C and 15N NMR spectroscopy

Abstract
The first example of cis–trans isomerism in monoalkylhydroxamic acids, detected by 1H, 13C and 15N NMR spectroscopy, is reported. The 15N NMR spectrum of CH3CO15NHOH gave a clear assignment of the OH and NH protons of both Z and E isomers. The assignment was confirmed by 1H and 13C NMR spectroscopy. A rotational barrier of isomerization (ΔGc≠) of 17.8 kcal mol−1 was calculated from the variable‐temperature 1H NMR spectra using the method of Shanan‐Atidi and Bar‐Eli.