Regiodivergent Synthesis and π‐Stacking‐Induced Chiral Self‐Recognition of Hexabenzocoronene‐Based [6]Helicenes
Futo Morita, Juntaro Nogami, Antônio Junio Araujo Dias, Suzuka Kinoshita, Yuki Nagashima, Ken Tanaka
Abstract
Abstract The lateral π‐extension of helicenes would yield interesting physical properties derived from the enhanced π‐stacking ability as well as intrinsic helical chirality. Here we report the regiodivergent synthesis of hexabenzocoronene (HBC)‐based [6]helicenes via cationic rhodium(I)/segphos complex‐mediated intramolecular [2+2+2] and [2+1+2+1] cycloadditions of triynes followed by Scholl reaction. The resulting HBC‐based [6]helicenes possess stable helical chirality but more planar structure than previously reported HBC‐based [7] and [9]helicenes. Therefore, these HBC‐based [6]helicenes exhibit π‐stacking‐induced chiral self‐recognition in solution, allowing the measurement of enantiomeric ratios by 1 H NMR spectroscopy without any chiral additive.