Synthesis of Thieno[3,2- b ]thiophene-Cored Hexacyclic Molecules Via the Pictet–Spengler Reaction

]thiophene bisquinoline derivatives via Pictet-Spengler reaction is reported, which were found to be highly versatile. Aromatic aldehydes afforded the desired products in moderate to good yields, with the observed reactivity depending strongly on the substitution pattern. In contrast, aliphatic aldehydes generated desired products only when the α-position of the benzylamine was blocked, while the open α-position yielded non-Pictet-Spengler reaction products, which is ascribed to aldehyde self-condensation or enol-mediated pathways.