Polyaromatic ribbons from oligo-alkynes via selective radical cascade: stitching aromatic rings with polyacetylene bridges.

Selective radical generation in conjugated oligomeric o-aryleneethynylenes initiates an intramolecular cascade which involves five fast radical cyclizations followed by aromatization via a 1,5-H shift with a >93% yield per step. This radical cascade transformation opens a new avenue for the systematic and controlled preparation of functionalized graphene nanoribbons where, potentially, each of the peripheral aromatic rings can be different.