Synthesis of thiophene derivatives via palladium-catalyzed coupling reactions

Thiophene derivatives with multiple substitutions are prepared from vinylidene bromide, which is synthesized by the reaction of thiophene-2-carboxaldehyde with carbon tetrabromide in the presence of PPh3, as a core molecule through several coupling reactions such as Suzuki–Miyaura coupling and palladium-catalyzed CH arylation. The reactions with a wide variety of organic halides lead to a series of substituted thiophene derivatives in moderate to good yields.