Synthesis of 6-(2’ or 4’- nitrophenyl)benzo[b]thiophenes by Palladium-catalyzed cross-coupling

The palladium-catalyzed cross-coupling reactions of organoboron compounds are very useful for carbon-carbon bond formation. Compounds 1 were synthesized by a palladium-catalyzed cross-coupling of bromo or iodonitrobenzenes with boronic esters 2, which were prepared from methylated 6- bromobenzo[b]thiophenes2 by halogen-metal exchange and transmetalation. The intermediates esters 2 were not isolated but directly, after evaporation of the ether, coupled in acetone/water using palladium acetate in the presence of sodium hydrogencarbonate. Yields of isolated compounds 1 were about 40%

Synthesis of diarylamines in the benzo[b]thiophene series bearing electron donating or withdrawing groups

The synthesis of diarylamines has attracted a great deal of interest due to their importance in diverse fields as natural biological active products and analogues, photography and materials science. Herein we report the synthesis of diarylamines 1 bearing electron donating or withdrawing groups by palladium catalyzed amination, in good yields (50%-quantitative yield) using two different bases and choosing the right components

Palladium-catalyzed amination of electron-rich or poor benzo[b]thienyl bromides

Recently we have applied the palladium-catalyzed amination to the synthesis of ortho-bromodiarylamincs in the benzo[blthiophene series . Here we describe the application of this methodology to the amination of electron-rich or poor 3-bromobenzo[b}thiophcnes, using the same conditions for both cases

Evaluation of the antioxidant properties of diarylamines in the benzo[b]thiophene series by free radical scavenging activity and reducing power

The antioxidant properties of substituted diarylamines in the benzo[b]thiophene series were evaluated by their reducing power and free radical scavenging activity. The results were compared with those of standards: acid ascorbic for the first method and BHA and BHT for the second. For both methods it was possible to establish some structure–activity relationships (SARs) based on the position of the arylamination on the benzo[b]thiophene moiety, the presence of different substituents on the phenyl ring (F, 1 or 2 OMe) and on the thiophene ring (H, CO2Et, CO2H)

Synthesis of the first thieno-δ-carboline. Fluorescence studies in solution and in lipid vesicles

The first thieno-δ-carboline (6,8,9-trimethyl-5H-pyrido[3,2-b]thieno[3,2-f]indole) was prepared in good yield (70%) by intramolecular palladium-assisted cyclization of an ortho-chlorodiarylamine. The latter was in turn selectively synthesized in high yield (90%) by C–N palladiumcatalyzed cross-coupling of 3-bromo-2-chloropyridine with, the also prepared, 6-amino-2,3,7-trimethylbenzo[b]thiophene. Fluorescence studies in solution show that thieno-δ-carboline has a solvatochromic behaviour. Despite the low fluorescence quantum yields in solution, studies of its incorporation in lipid vesicles of DPPC, DOPE and DODAB indicate that thienocarboline is located mainly inside the lipid bilayer, exhibiting different behaviours in gel or liquid-crystalline phases. Our studies are useful for the incorporation of thienocarboline in liposomes and for controlled drug release assays, due to its biological activity

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.).info:eu-repo/semantics/publishedVersio

Synthesis and antimicrobial activity studies of ortho-chlorodiarylamines and heteroaromatic tetracyclic systems in the benzo[b]thiophene series

ortho-Chlorodiarylamines in the 2,3,7-trimethylbenzo[b]thiophene series were prepared in high yields (70–85%) by C–N palladium-catalyzed cross-coupling using P(t-Bu)3 as ligand and NaOt-Bu as base. A palladium-assisted C–C intramolecular cyclization of the coupling products gave thienocarbazoles and the dechlorinated diarylamines. Studies of antimicrobial activity of the compounds obtained, against representative species of bacteria (Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus and Bacillus subtilis) and fungi (Candida albicans), were performed. We have also included in the biological assays some pyridine derivatives previously prepared by us, and it was possible to establish some structure–activity relationships (SARs)

Synthesis of potential anti-tumoral ring a substituted tieno[3,2-c]carbazoles from diarylamines

Thienocarbazoles bearing electron donating or withdrawing groups in ring a, were prepared by intramolecular oxidative cyclization of diarylamines using stoichiometric or catalytic Pd(OAc)2 amounts, in fair to moderate yields. ln the latter case Cu(OAch was added to reoxidize Pd(O) forrned. The diarylamine precursors were prepared by palladium-catalysed amination

Palladium-catalyzed cyclisation-deprotection of o-halodiarylacetamides, obtained by C-N copper assisted coupling, to the corresponding 6H-Thieno-[2,3-c]carbazole

With the aim of obtaining potential anti-tumoural thienocarbazoles by a ring B convergent method of synthesis, o-halodiarylacetamides were prepared by copper assisted C-N coupling' from 2-bromo-iodobenzene and 6-acetamido-2,3,5-trimethylbenzolb]thiophene, prepared from the 6-acetyl compound