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|Title:||Novel synthetic routes to thienocarbazoles via palladium or copper catalyzed amination or amidation of arylhalides and intramolecular cyclization|
|Author(s):||Ferreira, Isabel C. F. R.|
Queiroz, Maria João R. P.
|Citation:||"Tetrahedron". 58 (2002) 7943-7949.|
|Abstract(s):||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.|
|Appears in Collections:||CDQuim - Artigos (Papers)|