Twisted Polycyclic Arenes\nby Intramolecular Scholl\nReactions of C3-Symmetric Precursors

Abstract

With the aim of opening an efficient access to large\nand sterically\ncrowded polycyclic arenes as well as improving insight into the geometrical\npreferences of the Scholl reaction, a versatile synthesis strategy\nhas been developed to form a family of flexible yet strongly crowded\nsubstrates for multiple dehydrocyclizations. Their intramolecular\nScholl reactions lead with high selectivity either to considerably\ntwisted species where the initial C3 symmetry is maintained, or to\nstrongly rearranged products where the formation of multiple [6]­helicene\nfragments is avoided by the formation of unusual hexa[7]­circulene\nmoieties under loss of the C3 symmetry.