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.