Synthesis of 1,6-, 2,7-, 3,8-, and 4,9-Isomers of Didodecyl[1]benzothieno[3,2-b][1]benzothiophenes

The synthesis of 1,6-, 2,7-, 3,8-, and 4,9-isomers of dibromo- and didodecyl[1]benzothieno[3,2-b][1]benzothiophenes, via the stilbene pathway, is described. Starting from the synthesis of bromo-2-(methylthio)benzaldehydes, a series of functionalization, McMurry coupling, and finalising cyclization reactions were explored. The stereochemistry of the cyclization mechanism was investigated. Using this methodology didodecyl[1]benzothieno[3,2-b][1]benzothiophenes were formed in overall yields of 5-32%.