Synthesis and functionalization of novel tetrathia[7]helicenes as new push-pull systems

The synthesis of functionalized 1,2-bis(benzodithienyl)ethenes and the prepn. of the corresponding tetrathia[7]helicenes are described. The helicenes reported are chiral push-pull mols., with potential application in optoelectronics. Functionalized tetrathia[7]helicenes are obtained in good yields by application of two different synthetic strategies: (1) introduction of functionalized groups onto the alkene precursor followed by photochem. cyclization or (2) direct functionalization of the helicene.