Synthesis, Crystal Analyses, and Chiroptical Properties of Coumarin-Containing Helicenes

Four novel coumarin-containing arenes bearing a [5]/[6]helicene unit (5, 7, 11, and 13) have been readily synthesized and structurally verified by X-ray crystallographic analysis. The chiral resolution of molecules 7, 11, and 13 has enabled a detailed investigation of their chiroptical properties and the kinetics of enantiomerization, manifesting that the [6]helicenes 11 and 13 exhibit a more enhanced chiroptical response compared to [5]helicene 7.