Reaction of 1-amino-, 2-amino-, and 1,2-diaminoimidazoles with β-diketones

1,2-Diamino-4-phenylimidazolium perchlorate condenses with 2 mole of β-diketones to give pyrimido2′,1′:2,3]imidazo1,5-b]pyridazinium derivatives, while, like 1-amino-2-mercapto-4-phenylimidazole, to give imidazo1,5-b]pyridazine derivatives. Salts of 1-benzylideneamino- and 1-(2-thiazolyl)-2-aminoimidazoles react with β-diketones to give substituted imidazo1,2-a]pyrimidinium derivatives.