Nuclear Magnetic Resonance Spectroscopy. Analysis of the Proton Spectrum of Cyclobutene

A complete analysis of the proton n.m.r. spectrum of cyclobutene (I) has been made which shows that the couplings between the allylic and vinylic protons, while small, are by no means negligible; J_(13) = -0.80 C.P.S. and J_(15) = + 1.55 C.P.S. The analysis which involved ^(13)C satellite spectra of ordinary and specifically deuterated cyclobutene gave spin coupling and chemical shift parameters which predict that cyclobutene should show just two quite sharp peaks in its high-resolution n.m.r. spectrum in agreement with experiment.