KO^<i>t</i>Bu-Initiated Aryl C–H Iodination: A Powerful Tool for the Synthesis of High Electron Affinity Compounds

An efficient iodination reaction of electron-deficient heterocycles is described. The reaction utilizes KOtBu as an initiator and likely proceeds by a radical anion propagation mechanism. This new methodology is particularly effective for functionalization of building blocks for electron transport materials. Its utility is demonstrated with the synthesis of a new perylenediimide–thiazole non-fullerene acceptor capable of delivering a power conversion efficiency of 4.5% in a bulk-heterojunction organic solar cell.