Facile preparation of polycyclic halogen-substituted 1,2,3-triazoles by using intramolecular Huisgen cycloaddition

When 1-(ω-azidoalkyl)-2-(2,2-dihalovinyl)arenes were heated in DMF, the intramolecular Huisgen cycloaddition of an azido group with a 1,1-dihalovinyl group afforded 5-halo-1,2,3-triazole-fused tricyclic benzo compounds. Based on the remaining bromo groups, carbon elongation by the Mizoroki-Heck or Suzuki-Miyaura coupling reactions, followed by an intramolecular Friedel-Crafts reaction, afforded polycyclic compounds with fused triazole rings. Thereafter, the bromo groups were converted into 2-nitrophenyl groups via the Suzuki-Miyaura coupling reaction, which was followed by the Cadogan reaction; a fluorescent pentacyclic compound was obtained.