Tetrakis(2-thienyl)allene and 1,1,3,3-Tetrakis(2-thienyl)allyl Cation, an Electron-Rich Reactive Tetraarylallene and a Remarkably Stable Tetraaryl-Substituted Allyl Cation.

Abstract Tetrakis(2-thienyl)allene was synthesized as an acid-sensitive tetraarylallene by dehydration of the corresponding tetrathienylallyl alcohol with anhydrous copper(II) sulfate. This electron-rich allene forms a remarkably stable tetrathienylallyl cation by protonation, undergoes Diels-Alder reaction with tetracyanoethylene, and is capable of tetrafold lithiation and functionalization.