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 Pd-II-catalyzed dehydrogenative C(sp(2))-H/C(sp(3))-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 Pd-0-catalyzed C(sp(3))-H arylation. (C) 2012 Elsevier Ltd. All rights reserved.