Synthetic Access to Indolo[2,3-d]tropone-Derived Tolanes and Synthesis of Indolo[2,3-d]tropolones

Abstract Indolo[2,3-d]tropones or indolo[2,3-d]tropolones are formally assembled by an annulative merger of tropone or α-tropolone and indole. Although indolo[2,3-d]tropone or indolo[2,3-d]tropolone are derivatives of the popular cyclohepta[b]indole, their chemical, biological, and physical properties have not yet been evaluated. We reveal a modular, robust, and scalable synthetic access to indolo[2,3-d]tropone-derived tolanoids by adapting established chemistry, namely the alkyne-de Mayo reaction and the Sonogashira coupling. Furthermore, a method for the single-step oxidation of 6,7-dihydroindolo[2,3-d]tropones to indolo[2,3-d]tropolones is introduced.