Synthesis of the benzo[b]fluorene core of the kinamycins by cycloaromatization of non-conjugated benzotriynes

Article abstract of DOI:10.1016/S0040-4039(99)01570-1

Non-conjugated benzotriynes 2 undergo a novel radical cycloaromatization to provide the benzo[b]fluorene core of the kinamycins. The overall process involves a thermal intramolecular cyclization to the non-benzenoid biradicals 4 followed by radical cyclization and hydrogen abstraction.