Thiourea derivatives ofΒ-dicarbonyl compounds

Under the action of sulfuric acid, N-(2-phenylindan-1,3-dion-2-yl)-thioureas (I) undergo hydrolytic cleavage of the five-membered ring with the subsequent cyclization of the intermediate products formed, thiocarbomido-o-carboxydeoxybenzoins, to give 4-(o-carboxyphenyl)-5-phenylimidazole-2-thiones (III). The structure of compounds III has been confirmed by their IR and UV spectra, and a mechanism for their formation has been proposed. A preparative method for the synthesis of 4-(o-carboxyphenyl)-5-phenylimidazole-2-thiones has been developed.For communication IV, see 16].