An exclusive thiophene-fused polycyclic π-conjugated 2-arylbenzo[4,5]thieno[2,3-d]thiazoleskeleton was constructed via a one-pot CuCl-mediated three-componentreaction, using 2-(2-bromophenyl)acetonitrile and aromatic aldehydes as substrates and elemental sulfur as sulfur source in the presence of K2CO3 and 1,10-phen in DMSO. A plausible reaction mechanism was proposed, which involved formation of