A Facile Access to Novel (5+5) Annellated Heterocycles: Synthesis of a Furopyrrole, an Imidazoimidazole and a Pyrroloimidazole

We describe the synthesis of an ethyl 3-aryl-6H-furo[2,3-b]pyrrole-5-carboxylate 2, a 5-aryl-1H-imidazo[1,2-a]imidazole 3, and an ethyl-1-aryl-1,4-dihydropyrrolo[2,3-d]imidazole-5-carboxylate 4 as new hinge-binding motifs for PI3K kinase inhibitors. A key reaction for the formation of 2 and 4 is the Hemmetsberger–Knittel cyclization of acryloazides. The core of 3 is accessible through reaction of an α-haloketone with 2-aminoimidazole.