NMR spectroscopic characterization of ZE isomers of cyclododeca‐1,5,9‐triene

Abstract

AbstractThe four ZE isomers of cyclododeca‐1,5,9‐triene were examined by 13C NMR spectroscopy. The vicinal 1H1H coupling constants of the olefinic protons were used to determine the stereochemistry at the double bonds. For the symmetrically substituted CHCH fragments (chemically equivalent H atoms) this parameter was obtained from the 13C NMR multiplets which are observed in 1H continuous‐wave off‐resonance 13C NMR experiments. The precise assignment of the 1H and 13C chemical shifts, in particular for the Z,Z,E and Z,E,E isomers, was possible on the basis of off‐resonance measurements in combination with 13C/1H heteronuclear correlated and 1H/1H‐COSY‐45 2D experiments.