Novel synthetic routes to thienocarbazoles via palladium or copper catalyzed amination or amidation of arylhalides and intramolecular cyclization

• Autor(a) principal: Ferreira, Isabel C. F. R.
• Data de Publicação: 2002
• Outros Autores: Queiroz, Maria João R. P., Kirsch, G.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: https://hdl.handle.net/1822/2255
• topic: C-N coupling; Copper; Palladium; Cyclization-deprotection; Thienocarbazoles; Science & Technology

Palladium or copper catalyzed aminations or amidations were performed to obtain diarylamines and diarylacetamides precursors of thienocarbazoles. The fact that an ortho-bromodiarylamine didn’t cyclize to the corresponding thienocarbazole under conditions known for carbazoles from ortho-halodiphenylamines, conducted us to a highgly efficient method of palladium-catalyzed intramolecular cyclisation with N-deprotection of ortho-halodiarylacetamides to thienocarbazoles. Other method of intramolecular cyclization of diarylamines based on the reoxidation of the Pd(0) formed by Cu(OAc)2 , avoiding the use of stoichiometric amounts of Pd(OAc)2, gave thienocarbazoles in a moderate yield, including a ring A methoxylated compound. An attempt to combine palladium and copper catalyses in a “one pot” reaction of amination and intramolecular cyclization gave as major product a N-benzo[b]thiophene substituted carbazole and the required thienocarbazole in low yield.