1H nuclear magnetic resonance spectra of the imidazo[2,1-b]thiazole system

Abstract

Some imidazo[2,1-b]thiazoles have been subjected to a ¹H n.m.r. investigation. The aromatic character of this ring system, in connection with proton shielding, has been tested with coupled Hartree–Fock calculations of ring current effects, and it seems that the main differences in the chemical shifts relative to the single ring heterocycles are due to this kind of perturbation. A long-range coupling constant over six bonds has also been observed which implies a coupling mechanism involving the sulphur atom.