Imidazole-2-Thiones: Synthesis, Structure, Properties

Abstract The literature data concerning the methods for preparing imidazole-2-thiones and their benzo analogs have been systematized, and the structure, physico-chemical properties and chemical conversions of these compounds have been considered. The methods for the synthesis of imidazole-2-thiones are classified according to reaction types including cyclization, reactions of halo- and oxoimidazole derivatives with sulfur-containing nucleophiles, and direct insertion of sulfur into position 2 of the imidazole ring. The structure of imidazole-2-thiones is discussed in terms of quantum-chemical calculations, X-ray diffraction data, dipole moments, UV, and IR as well as 1H and 15N NMR spectroscopy. Much attention has been given to nucleophilic addition of imidazole-2-thiones to acetylene and its derivatives as well as to alkenes with an activated double bond. The reactions of imidazole-2-thiones as nucleophilic agents, including alkylation, acylation, and interaction with carbonyl halides are discussed. Some...