Environmental-friendly synthesis of oxazolines, imidazolines and thiazolines catalyzed by tungstophosphoric acid

A convenient and green method for the synthesis of aromatic 2-oxazolines, 2-imidazolines and 2-thiazolines using tungstophosphoric acid (TPA), a commercially available, stable and reusable catalyst, from the reaction of aromatic nitriles and 2-aminoalcohols, ethylenediamine or 2-aminoethanethiol under solvent-free conditions is reported. It is noteworthy that this procedure could be used for selective synthesis of mono- and bis-oxazolines and imidazolines from dicyanobenzene. In three cases the catalyst could be reused several times without significant loss of its catalytic activity.