Domino dehydrative π-extension : a facile path to extended perylenes and terrylenes

Abstract

Towards nanographenes: Domino-DPEX (dehydrative π-extension) is a new synthetic approach to extended nanographenes containing a perylene or terrylene core. The pronounced regioselctivity towards aldehyde groups in different positions makes DPEX an excellent tool for implementing pre-programmed multiple annulation of simple precursors of elusive nanographenes. This approach enables the formation of up to five C−C bonds in one-step in up to 94 % per C−C bond. Herein, we report a new method for synthesis of extended perylenes and terrylenes. The technique is based on the cascade dehydrative π-extensions (DPEX) of aryl aldehydes, in which stepwise annulations activate previously “dormant” substituents. Two- and fourfold cyclizations of 3-aryl-biphenyl-2,2′-dicarbaldehydes offer a rapid path to unsymmetrical perylenes and elusive terrylene derivatives, respectively. DPEX of 3,3′′-(phenanthrene-1,8-diyl)bis (([1,1′-biphenyl]-2,2′-dicarbaldehyde)) leads to the biradical structure, which proceeds in situ into oxidative electrocyclization at room temperature. The described domino process complements and expands DPEX approach to a large family of fused acenes and related PAHs.