One-pot synthesis of 4,8-dialkylbenzo[1,2-b:4,5-b']dithiophenes

Two-step, one-pot syntheses are described for the preparation of 4,8-dialkylbenzo[1,2-b:4,5-b']dithiophenes (BDTs) from alkyllithium or alkyl Grignard reagents. The yields for various alkyl groups used in this procedure are comparable with or exceed those of previously reported methods. The electronic and redox properties of dialkyl-BDTs are compared with the dialkoxy-BDT, 4,8-bis(hexyloxy)benzo[1,2-b:4,5-b']dithiophene. The stabilized HOMO levels of dialkyl-BDTs suggest they are promising building blocks for use in organic photovoltaics such as bulk heterojunction solar cells.