Nuclear magnetic resonance spectra of 1,4-Dihydro- 1,4-ethenoisoquinolin-3(2H)-ones

Abstract

The 100-MHz N.M.R. spectra of four 1,4-dihydro-1,4-ethenoisoquinolin- 3(2H)-ones were analysed and the relative signs of vicinal and allylic coupling constants were determined in one of the series. The allylic coupling constants include the largest positive value so far reported and appear to vary with substitution in a manner analogous to that exhibited by coupling constants between meta protons in benzene derivatives.