Palladium-catalyzed direct oxidative vinylation of thiophenes and furans under weakly basic conditions

The palladium-catalyzed oxidative coupling of thiophenes and furans with alkenes proceeds in the presence of copper and lithium salts as oxidant and additive, respectively, under weakly basic or almost neutral conditions to afford the corresponding vinylated heteroarenes. Under such conditions, diphenyl(hydroxy)methyl and acetal functions on the heteroarene substrates are tolerable. The former function on a thiophene ring can be substituted by palladium-catalyzed arylation via C-C bond cleavage after the vinylation to produce 2-aryl-5-vinylthiophenes. (C) 2008 Elsevier Ltd. All rights reserved.