Direct arylation of Thiophenes via palladium-catalysed C-H functionalisation at low catalyst loadings

Palladium associated with cis,cis,cis-1,2,3,4tetrakis(diphenylphosphinomethyl)cyclopentane (Tedicyp) was found to promote the direct 2-arylation of a variety of thiophene derivatives via C-H functionalisation in good yields using very low catalyst loadings. Electron-deficient, electron-excessive or sterically-congested aryl bromides are tolerated. Moreover, several substituents on the aryl bromide or thiophene derivatives such as acetyl, formyl, nitrile, nitro, ester, methoxy, fluoro or trifluoromethyl are tolerated. The most reactive aryl bromides were coupled with thiophenes derivatives using as little as 0.1-0.01 mol% catalyst.