Benzo [b] thiophenes are prepared by intramolecular Pd (0)-catalyzed Heck reaction of allyl o-iodophenyl sulfides. Pd (0)-Catalyzed intramolecular cyclization of o-iodophenyl propargyl sulfide in the presence of a hydride donor gives 3-methylene-2, 3-dihydrobenzo [b] thiophene, which reacts with several enophiles in ene type reactions. However, allyl (and propargyl) aryl sulfides react with palladium (II) chloride to afford polymeric [PdCl (SAr)] 2.
[Kobayashi, Kazuhiro; Nakamura, Daizo; Miyamoto, Kazuna; Morikawa, Osamu; Konishi, Hisatoshi Bulletin of the Chemical Society of Japan, 2007 , vol. 80, # 9 p. 1780 - 1784]