Synthesis of 2-arylideneimidazo[1,2-a]pyrazine-3,6,8(2H,5H,7H)-triones as a result of oxidation of 4-arylidene-2-methyl-1H-imidazol-5(4H)-ones with selenium dioxide

4-Arylidene-2-methyl-1H-imidazol-5(4H)-ones with an acetamide substituent at position 1 of the imidazolone ring can be oxidized with selenium dioxide to form a six-membered imide ring. The spectra of the obtained 2-arylideneimidazo[1,2-a]pyrazine-3,6,8(2H,5H,7H)-triones exhibit significant bathochromic shifts of the absorption and emission maxima in comparison with the spectra of the starting imdazolones, which suggests that the synthesized compounds could be used as fluorogenic dyes.