Antiparasitic nitroimidazoles. Part V. Interpretation of the proton magnetic resonance spectra of olefinic protons by means of additive increments, Hammett correlations, and the effect of lanthanide shift reagents

Abstract

A number of 2-(substituted styryl)-5-nitro-N-substituted imidazoles possessing antiparasitic activity have been characterised by n.m.r. spectroscopy. A full assignment of the proton resonances has been carried out by use of (i) an additive increment method for chemical shift prediction, (ii) correlations with Hammett substituent constants (σ_I, σ_M, σ_R⁰), and (iii) quantitative measurements of chemical shifts induced in the title and model compounds by europium shift reagents.