Synthesis of 3a,4,6a-triphenylimidazothiazoledione and 2-thioxo-3a,6,6a-triphenylimidazooxazolone in the reaction of 5-hydroxy-1,4,5-triphenyl-1H-imidazol-2(5H)-one with KSCN and AcOH

The study of the reaction of 5-hydroxy-1,4,5-triphenyl-1H-imidazol-2(5H)-one with KSCN and AcOH showed that it leads to the formation of 3a,4,6a-triphenyltetrahydro-2H-imidazo[4,5-d]thiazole-2,5(3H)-dione (1a) and 2-thioxo-3a,6,6a-triphenyltetrahydro-2H-imidazo[4,5-d]oxazol-5(3H)-one (2b) with the predominant formation of the former one. The structures of compounds 1a and 2b were confirmed by X-ray diffraction analysis on the examples of solvate 1a center dot AcOH and monohydrate 2b center dot H2O obtained by crystallization from AcOH and a mixture of EtOH-H2O (1: 10), respectively.