A novel and efficient approach to (Z)-1,2-bis(benzodithienyl)ethene precursors of tetrathia[7]helicenes

A new and efficient method for the 'one-step' synthesis of (Z)-1,2-bis(benzodithienyl)ethenes has been set up using double Suzuki coupling between stereochemically defined diboronic acid esters and 2-iodo benzodithiophene. The new Z-alkenes thus obtained can be easily and efficiently photochemically cyclised to the newly substituted tetrathia[7]helicenes.