Tetrazo[1,2‐b]indazoles: Straightforward Access to Nitrogen‐Rich Polyaromatics froms‐Tetrazines

Abstract

AbstractThe straightforward access to a new class of aza‐polyaromatics is reported. Starting from readily available fluorinated s‐tetrazine, a cyclization process with azide leads to the formation of an unprecedented tetrazo[1,2‐b]indazole or a bis‐tetrazo[1,2‐b]indazole (cisandtransconformers). Based on the new nitrogen core, further N‐directed palladium‐catalyzedortho‐C−H bond functionalization allows the introduction of halides or acetates. The physicochemical properties of these compounds were studied by a joint experimental/theoretical approach. The tetrazo[1,2‐b]indazoles display solid‐state π‐stacking, low reduction potential, absorption in the visible range up to the near‐infrared, and intense fluorescence, depending on the molecular structure.