Efficient Pallado-Catalyzed C6-(het)arylation of Imidazo[1,2-b][1,2,4,5]Tetrazines under Microwave Irradiations

A versatile protocol for the preparation of a library of 5,6-(het)bisarylated imidazol[1,2,b][1,2,4,5]tetrazines is described. Target compounds were obtained in fairly good yields, starting from ethoxy-7-(4-methoxyphenyl)imidazo[1,2-b][1,2,4,5]tetrazine and a large panel of bromoaryl derivatives, using palladium catalysis under microwave irradiation. Compatibility with various chemical groups and heterocycles was proven. Steric and electronic effects do not have any effect on the efficiency of the reaction. Purifications were performed without any difficulties, and the structure of a final compound was proven by crystal X-ray diffraction studies.