Construction of 2-Arylbenzo[4,5]thieno[2,3-d]thiazole Skeleton via CuCl/S-Mediated Three-Component Reaction.

An exclusive thiophene-fused polycyclic π-conjugated 2-arylbenzo[4,5]thieno[2,3-d]thiazole skeleton was constructed via a one-pot CuCl-mediated three-component reaction, 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 benzo[b]thiophen-2-amines through cyclization of 2-bromophenyl acetonitrile and sulfur, and subsequent intramolecular condensation/dehydrogenation with aromatic aldehydes.