Intramolecular PdII-catalyzed dehydrogenative C(sp3)–C(sp2) coupling: an alternative to Pd0-catalyzed C(sp3)–H arylation from aryl halides?

The synthesis of fused thiophene–cyclopentanes by PdII-catalyzed dehydrogenative C(sp2)–H/C(sp3)–H coupling is described. This reaction shows interesting chemo- and diastereoselectivity, however a direct comparison showed that it is yet much less efficient than the two-step sequence composed of electrophilic halogenation and Pd0-catalyzed C(sp3)–H arylation.