Synthesis of Benzofuro- and Indolo[3,2‑<i>b</i>]indoles via Palladium-Catalyzed Double <i>N</i>‑Arylation and Their Physical Properties

Abstract

Two kinds of ladder-type π-conjugated compounds, benzofuro­[3,2-<i>b</i>]­indoles (BFIs) and indolo­[3,2-<i>b</i>]­indoles (IIs), were successfully synthesized using palladium-catalyzed double <i>N</i>-arylation of anilines with the corresponding dihalobiaryls. Photophysical properties were evaluated by UV–vis and photoluminescence spectroscopies and theoretical calculations. BFI derivatives showed higher quantum yields (33–39%) than the II derivative (29%). The absorption bands of the II derivative were more red-shifted compared to BFI derivatives