Unusual rearrangement of imidazo[1,5- a ]imidazoles and imidazo[1,2- b ]pyrazoles into imidazo[1,5- a ]pyrimidines and pyrazolo[1,5- a ]pyrimidines.

A multicomponent reaction giving easy and cheap access to a variety of bicyclic 5,5-fused hetero-rings has been developed. Then, an usual rearrangement of imidazo[1,5- a ]imidazoles or imidazo[1,2- b ]pyrazoles leading to bi-heterocyclic imidazo- and pyrazolo[1,5- a ]pyrimidines in the presence of a specific amount of I 2 in THF at room temperature has been achieved. This new method enables the hitherto unreported synthesis of functionalized imidazo- and pyrazolo[1,5- a ]pyrimidines.