Dioxygen‐Triggered Transannular Dearomatization of Benzo[5]helicene Diols: Highly Efficient Synthesis of Chiral π‐Extended Diones

Abstract

Oxidative dearomatization is a powerful strategy in organic synthesis. However, reports on using dioxygen as the oxidant, as it is environmentally friendly, readily available (air), and easy to handle, are rather limited. Helicene diols can undergo transannular dearomatization triggered by dioxygen to give diones in quantitative yields within several minutes. By virtue of this, the chirality is successfully transferred from helicity to central chirality to form distorted π-extended diones having two all-carbon quaternary stereocenters. The optical resolution was achieved by column chromatography, and the structures and the absolute configurations of the chiral diones were determined by X-ray analysis.