Conditions for the Palladium-Catalysed Direct 2-Arylation of 3-Bromobenzo[b]thiophene Tolerant of the Benzothienyl Carbon-Bromine Bond
Abstract
Phosphine-free palladium(II) acetate catalyst was found to promote the direct 2-arylation of 3-bromobenzo[b]thiophene without cleavage of the benzothienyl carbon-bromine bond, allowing the synthesis of 2-aryl-3-bromobenzo[b]thiophenes in only one step. The best results were generally obtained using a low loading of the palladium catalyst (0.5 mol%), quite low reaction temps. (80-120 °C) and short reaction times (0.5-2 h). The reaction proceeds with electron-deficient para-, meta- and ortho-substituted aryl bromides and also with heteroaryl bromides. The benzothienyl carbon-bromine bond has been profitably employed for further palladium-catalyzed functionalisations. This strategy allows the straightforward synthesis of 2,3-di(hetero)arylated benzo[b]thiophenes with two different (hetero)aryl units via sequential catalytic arylations.
Origin : Files produced by the author(s)
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