Synthesis and application of 3,4,7,8-tetrakis-exo-methylenecycloocta-1,5-diene as a versatile Diels–Alder diene: synthesis of V-shaped cyclooctatetraene fused acenes

Abstract

V-shaped molecules with a cyclooctatetraene (COT) core and rigid acene wings are an interesting class of compounds from the point of view of synthetic challenge and their applications in various fields such as photonics and molecular electronics. A new Diels–Alder diene, namely 3,4,7,8-tetrakis-exo-methylenecycloocta-1,5-diene (1), has been synthesized on a multigram scale by the debromination of 1,4,5,8-tetrakis-bromomethylcycloocta-1,3,5,7-tetraene (2) using either zinc powder or NaI. Compound 1 was used as a Diels–Alder diene with various dienophiles to yield the corresponding double Diels–Alder adducts. The Diels–Alder adducts have a COT core and dihydroaromatic wings which were aromatized with a variety of reagents. The methodology described herein provides a direct and shorter route for the synthesis of COT fused with rigid aromatic wings (V-shaped) compared to the existing iterative multistep synthesis of such compounds.