Synthesis, Resolution, and Stabilities of a Cationic Chromenoxanthene [4]helicene

1,13-Dimethoxychromenoxanthenium, a key intermediate in the synthesis of the classical trioxatriangulenium cation, was isolated and characterized for the first time. This [4]helicene was resolved through a CSP-HPLC procedure, with chemical and configurational stabilities being determined and compared.