Hexapole [9]Helicene

Abstract

This work presents the first hexapole [9]helicene (H9H). Co‐catalyzed [2+2+2] cyclotrimerization of a dinaphthopyrene (DNP) functionalized alkyne provides the hexaaryl benzene precursor 2, which is transformed into H9H via a dehydrocyclization reaction. Formation of each embedded [9]helicene involves forging of a new C‐C bond, which stitches together two [4]helicene subunits of the neighboring DNP blades, reminiscent of the initial method Martin developed for the preparation of [9]helicene in the 1960s. Single crystal X‐ray analysis of both 2 and H9H discloses their extremely distorted and crowded structural features. Chiral resolution, optical and electronic properties of H9H are also included.