Modular assembly of conformationally dynamic dinaphthocycloocta-1,5-dienes

Abstract

The integration of cyclooctene-derived motifs into larger molecular frameworks has emerged as a promising strategy to construct switchable molecules and materials that rely on conformational changes of the central eight-membered ring. In this work, we developed a facile synthetic route to access dinaphthocycloocta-1,5-dienes (DNCODs) relying on Lewis acid-catalyzed inverse electron-demand Diels–Alder (IEDDA) reactions of phthalazines and cyclooct-1-en-5-yne derivatives. By employing two sequential IEDDA reactions, the modular annulation of different naphthalene units to the cyclooctadiene core was achieved. While the resulting DNCODs were found to adopt a chair conformation in the crystalline state, variable temperature (VT) NMR spectroscopy revealed a dynamic equilibrium in solution, with the twist-boat conformer being favoured. These findings offer new opportunities for engineering switchable cyclooctene-based structures and integrating them into functional materials.