Convergent Strategy for the Synthesis of Oxa‑, Thia‑, and Selena[5]helicenes by Acetylene-Activated SNAr Reactions

A tandem acetylene-activated SNAr-anionic cyclization strategy is presented for the synthesis of chalcogen-containing hetero[5]­helicenes. Oxa-, thia-, and selena[5]­helicenes are accessed from common ortho-fluoro-ethynylarene precursors, allowing the heteroatoms to be installed at the 1-position or 1- and 12-positions of the hetero[5]­helicene inner core surface.