Cyclization of 1,3-dialkyl-4,5-bis(1-thiosemicarbazido)-imidazolidin-2-ones(thiones) with aromatic aldehydes

Cyclization of 1,3-dialkyl-4,5-bis(1-thiosemicarbazido)imidazolidin-2-ones(thiones) with aromatic aldehydes under acidic catalysis affords 1,3-dialkyl-4-(arylideneamino)-5-thioxohexahydroimidazo[4,5-d]imidazol-2(1H)-ones and 5,7-dialkyltetrahydro-1H-imidazo[4,5-e]-1,2,4-triazine-3,6(2H,4H)-dithiones.