200358-08-3Relevant articles and documents
Ligand-less palladium-catalyzed direct 5-arylation of thiophenes at low catalyst loadings
Roger, Julien,Pozgan, Franc,Doucet, Henri
experimental part, p. 425 - 432 (2010/04/22)
Ligand-less Pd(OAc)2 provides a very efficient catalyst for the direct 5-arylation of thiophene derivatives. With this catalyst, a low palladium concentration (0.1-0.001 mol%) should be employed in order to obtain high yields of coupling products. At higher concentrations a fast formation of inactive "Pd black" generally occurs. Substrates/catalysts ratios up to 100000 can be employed with the most reactive aryl bromides. A very wide variety of functional groups is tolerated on both coupling partners. The major waste of this reaction is HBr associated with KOAc. Therefore this procedure is more economically and environmentally attractive than the traditional cross-coupling procedures employing organometallic derivatives.
Extension of the Heck reaction to the arylation of activated thiophenes
Lavenot,Gozzi,Ilg,Orlova,Penalva,Lemaire
, p. 49 - 55 (2007/10/03)
The direct arylation of activated thiophenes was accomplished in moderate to good yields using a Heck-type reaction with the mixture of Pd(OAc)2 and n-Bu4NBr as a catalytic system. This new arylation method is applied to different derivatives and has proved to be compatible with sensitive functional groups. Furthermore, the substituent nature and position on the thiophene moiety influence the cross coupling. In particular the substitution is regiospecific when the heterocycle is substituted at position 2 with an electron withdrawing group.
