Synthesis of novel twisted heterocyclic analogues of s-indacenes

A series of novel compounds as candidates for OLED applications were synthesized by cyclization reactions of neighbouring rings in dipyrazolo[3,4-b:4',3'-e]pyridines 8-12. The desymmetrization of these molecules leading to 14 can be performed using both KOH/isoquinoline or palladium catalysts. The resulting structures contain a helical arrangement of four different rings