One-pot formation of piperidine- and pyrrolidine-substituted pyridinium salts via addition of 5-alkylaminopenta-2,4-dienals to N-acyliminium ions: application to the synthesis of (±)-nicotine and analogs

Addition of 5-alkylaminopenta-2,4-dienals onto N-acyliminium ions, generated in situ from α-hydroxycarbamates derived from pyrrolidine or piperidine, in the presence of zinc triflate, followed by dehydrative cyclization, allowed the formation of pyridinium salts substituted at their 3-position by a five- or six-membered nitrogen heterocycle. Subsequent N-dealkylation of the pyridinium moiety and deprotection of the secondary amine or reduction of the carbamate function led to (±)-nicotine and analogs.     

Green,lithium salt-free synthesis of 2-alkylated 1,4-benzenediols in hydroalcoholic media

Herein, we describe an efficient, green, and lithium salt-free synthesis of 2-substituted 1,4-benzenediol in water/ethanol as solvent and potassium carbonate as a base. Optimized reaction time, the required equivalent of base and the observed solvent effect are reported.     

Characterizing magnetic interactions in Ni nanowires by FORC analysis

Polycrystalline Ni nanowires with different diameters were electrodeposited in nanoporous anodized alumina membranes. First-Order Reversal Curves (FORCs) were measured and FORC distributions were calculated. They clearly showed an asymmetric behavior with a strong maximum at negative interaction fields, evidencing the dominant demagnetizing interactions which depend on the geometry of the nanowires.     

The ultrastructure of infective larvae (L3) of Wuchereria bancrofti after treatment with diethylcarbamazine

Although the large use of diethylcarbamazine (DEC), as the major anti-filaricide drug, its mechanism of action remains a matter of controversy. Several authors defend the hypothesis that DEC has no direct effect on nematodes. This study demonstrated that infective larvae (L3) of Wuchereria bancrofti treated in vitro with DEC presented several behaviour and morphological changes. The first alteration produced by treatment for 2 h with 3, 5, 10 microg/ml of DEC was the reduction of motility. Larvae treated with 5, 10 microg/ml DEC showed severely affected organelles, formation of several vacuoles, mainly in neurocytes and in the muscle cells, and dissolution of cytoplasm. Some larvae showed extreme cellular disorganization with abundance of large and dense mitochondria and numerous large vacuoles containing residual organelles. Lamellar bodies, probably related to an assembly of hipodermal membranes, were also observed in some damaged larvae. Thus, undoubtedly in vitro treatment with concentrations of DEC similar to therapeutic conditions, which are 1-5 microg/ml (Hawking, 1979), had a direct effect on infective larvae of W. bancrofti by causing, primarily neuromuscular alterations with subsequent damage to organelles.     

Geometry in the Entanglement Dynamics of the Double Jaynes–Cummings Model

We report on the geometric character of the entanglement dynamics of two pairs of qubits evolving according to the double Jaynes–Cummings model. We show that the entanglement dynamics for the initial states | ψ ₀〉 = cos α | 10〉 + sin α | 01〉 and | ? ₀〉 = cos α | 11〉 + sin α | 00〉 cover three-dimensional surfaces in the diagram C _ij × C _ik × C _il , where C _mn stands for the concurrence between qubits m and n, varying 0 ≤ α ≤ π / 2. In the first case, projections of the surfaces on a diagram C _ij × C _kl are conics. In the second case, curves can be more complex. We relate those conics with a measurable quantity, the predictability. We also derive inequalities limiting the sum of the squares of the concurrence of every bipartition and show that sudden death of entanglement is intimately connected to the size of the average radius of a hypersphere.     

Regio- and stereoselective Heck arylations of N-carbomethoxy-L- 3-dehydroproline methyl ester with arenediazonium salts. Total synthesis of neuroexcitatory aryl kainoids

The Heck arylation of N-carbomethoxy-L-3-dehydroproline methyl ester with arenediazonium tetrafluoroborates produced chiral 4-aryldehydroproline derivatives in moderate to good yields in a highly regio- and stereocontrolled fashion. A rationale for the unexpected high regioselectivity is provided using Deeth's model. Heck adduct 15 (G = o-CH3O) was converted into several aryl kainoids using concise and efficient routes.     

Antileishmanial activity of the hydroalcoholic extract of Miconia langsdorffii, isolated compounds, and semi-synthetic derivatives

The in vitro activity of the crude hydroalcoholic extract of the aerial parts of Miconia langsdorffii Cogn. was evaluated against the promastigote forms of L. amazonensis, the causative agent of cutaneous leishmaniasis in humans. The bioassay-guided fractionation of this extract led to identification of the triterpenes ursolic acid and oleanolic acid as the major compounds in the fraction that displayed the highest activity. Several ursolic acid semi-synthetic derivatives were prepared, to find out whether more active compounds could be obtained. Among these ursolic acid-derived substances, the C-28 methyl ester derivative exhibited the best antileishmanial activity.     

Aminodi(hetero)arylamines in the thieno[3,2-b]pyridine series: synthesis, effects in human tumor cells growth, cell cycle analysis, apoptosis and evaluation of toxicity using non-tumor cells

Three aminodi(hetero)arylamines were prepared via a palladium-catalyzed C-N Buchwald-Hartwig coupling of methyl 3-aminothieno[3,2-b]pyridine-2-carboxylate with different bromonitrobenzenes, followed by reduction of the nitro groups of the coupling products to the corresponding amino compounds. The aminodi(hetero)arylamines thus obtained were evaluated for their growth inhibitory effect on four human tumor cell lines MCF-7 (breast adenocarcinoma), A375-C5 (melanoma), NCI-H460 (non-small cell lung cancer) and HepG(2) (hepatocellular carcinoma). The toxicity to non-tumor cells was also evaluated using a porcine liver primary cell culture (PLP1), established by us. The aminodi(hetero)arylamine with the NH(2) group in the ortho position and an OMe group in the para position to the NH of the di(hetero)arylamine, is the most promising compound giving the lowest GI(50) values (1.30-1.63 μM) in all the tested human tumor cell lines, presenting no toxicity to PLP1 at those concentrations. The effect of this compound on the cell cycle and induction of apoptosis was analyzed in the NCI-H460 cell line. It was observed that it altered the cell cycle profile causing a decrease in the percentage of cells in the G0/G1 phase and an increase of the apoptosis levels.