Catalytic cyclotrimerization routes to symmetrical [9]helical indenofluorene were explored by using different transition-metal complexes and thermal conditions. Depending on the reaction conditions, the cyclotrimerizations were accompanied by dehydro-Diels-Alder reaction giving rise to another type of aromatic compounds. Structures of both symmetrical [9]helical cyclotrimerization product as well as the dehydro-Diels-Alder product were confirmed by single-crystal X-ray diffraction analyses. Limits of enantioselective cyclotrimerization were assessed as well. DFT calculations shed light on the reaction course and the origin of diminished enantioselectivity.

• Keywords
• C−C bond cleavage, [9]helical structure, catalysis, cyclotrimerization, dispiroindenofluorenes,
• Publication type
• Journal Article MeSH