Sterically Crowded Heterocycles. IX. New α,β-Unsaturated Ketones Containing Imidazo[1,2- a ]quinoline, Imidazo[2,1- a ]isoquinoline, Benzo[ h ]imidazo[1,2- a ]quinoline and Imidazo[1,2- a ]-1,10-phenanthroline Moieties
( Z )-1,3-Diphenyl-3-(2-phenylimidazo[1,2- a ]heteroaryl)prop-2-en-1-ones 2-6 and isomeric [1-heteroaryl-3,5-diphenylpyrrol-2-yl]phenylmethanones 17-20 were prepared by the ferricyanide oxidation of quaternary pyridinium salts 12-16 . Axial chirality and helicity of the molecules of 4 and 6 are discussed using various energy data obtained by the quantum chemical PM3 method.