Concise Synthesis of Polysubstituted Carbohelicenes by a C-H Activation/Radical Reaction/C-H Activation Sequence.

Disclosed herein is the merging of C-H activation and radical chemistry, enabling rapid access to a structurally diverse family of fused carbohelicenes through the fusion of α-acetylnaphthalenes with alkynes under oxidative conditions. This cascade process exhibits exquisite chemoselectivity and regioselectivity. The reaction pathway was analyzed by intermediate separations, control experiments, radical trapping, EPR, MALDI-TOF-MS, and ESI-HRMS experiments, and shown to involve a C2-H activation/radical reaction/C8-H activation relay.