Spectroscopic characterization of 1‐methylene‐2‐vinylcyclopropane and some of its derivatives

Abstract

AbstractThe characteristic NMR and vibrational spectroscopic properties of 1‐methylene‐2‐vinylcyclopropane 1 and some of its derivatives are described and discussed. The exocyclic CC stretching vibration is consistently found at 1745 cm−1. The 1H NMR spectra show coupling patterns among the methylene and ring protons that are essentially independent of the substituents. The coupling constant between H‐2 and the α‐proton of the substituent depends on the conformation. 13C chemical shifts and coupling constants are readily interpreted using common substituent effect rules. MNDO calculations provide proton‐proton distances and bond orders which are used to interpret proton relaxation rates and proton‐proton coupling constants.