Using 2,2′-dibromo-5,5′-bis(trimethylsilyl)-3,3′-bithiophene(3)as starting material,the main product cyclooctatetrathiophene(TMS_4-COTh-1)and the side product cyclododecahexathiophene(TMS_6-2)were obtained by Br/Li exchange and following copper(II)chloride oxidative coupling.By changing the reaction solvent from diethyl ether to tetrahydrofuran,the yields of TMS_4-COTh-1 were improved from the reported 40%to 69%,while the side product TMS_6-2 was disappeared.This reaction shows high efficient solvent-select...