Tandem palladium-catalyzed borylation and Suzuki coupling (BSC) to thienocarbazole precursors

Substituted 2-methyl-2 -nitro diaryl compounds in the benzo[b]thiophene series were prepared by palladium-catalyzed, two-step, one-pot borylation/Suzuki coupling (BSC) reaction in good to high yields. The borylation reaction was performed on methylated 6-bromobenzo[b]thiophenes using pinacolborane and was followed by in situ Suzuki coupling with substituted (CF3, OMe) 2-bromonitrobenzenes. The compounds obtained were cyclized to the corresponding ring A substituted thienocarbazoles which can have biological activity or/and be used as biomarkers due to their fluorescence properties and possible DNA intercalation.Thanks are due to the Foundation for Science and Technology, IBQF, University of Minho (Portugal), to the Research Incitment Programme of the Calouste Gulbenkian Foundation (Portugal) for financial support and to the Escola Superior Agra ´ria, Instituto Polite ´cnico de Braganc ¸a for supporting in part I.C.F.R.F. (Ph.D.).