Palladium-Catalysed Direct Monoarylation of Bithiophenyl Derivatives or Bis(thiophen-2-yl)methanone with Aryl Bromides

Arylated bithiophenes, which are useful compounds due to their coordination and/or physical properties, can be easily prepared by palladium‐catalysed C–H bond activation of heteroaromatics followed by arylation using electron‐deficient aryl bromides. A variety of 5‐arylated 2,2′‐bithiophenyl derivatives have been prepared. Good yields were generally obtained by using the air‐stable [PdCl(dppb)(C3H5)] complex as catalyst. A range of functions on the aryl bromide, such as acetyl, formyl, ester, nitrile, trifluoromethyl, fluoro and hydroxyalkyl, are tolerated. The palladium‐catalysed direct monoarylation at C‐5 of bithiophene derivatives with aryl bromides proceeds smoothly by using a low loading of an air‐stable catalyst in combination with a cheap and non‐toxic base.