Synthesis of 1,8-naphthyridines and their application in the development of anionic fluorogenic chemosensors.

Two 1,8-naphthyridines were synthesized and found to be fluorescent in solution. These compounds were studied in the presence of Cu(+) and Cu(2+) ions and it was verified that the metal causes the quenching of their fluorescence emission, due to the formation of complexes between the naphthyridine and the metal. A displacement assay was carried out in a DMSO-water mixture with the addition of various anions to the solutions of the complexes, and it was observed that these systems have a high capacity to selectively detect cyanide.

Synthesis of N-[(3S)-2,6-dioxo-1-(2-phenylethyl)-3-piperidinyl]-(2S)-2-methylbutanamide ((-)-julocrotine).

The total synthesis of (-)-julocrotine (1) starting from l-glutamic acid in 41% overall yield is described. The methodology utilizes protection, deprotection, and regioselection (carbonyl differentiation via oxazolidinone) protocols, and glutarimide ring formation is the key step.

[(1R*,2S*)-N-Benzyl-2-phenyl-1-(pyridin-2-yl)-N-(pyridin-2-ylmeth-yl)ethane-1,2-diamine]-dichloridozinc(II).

In the mononuclear zinc title complex, [ZnCl(2)(C(26)H(26)N(4))], the Zn(II) ion is surrounded by three N atoms from a (1R*,2S*)-N(1)-benzyl-2-phenyl-1-(pyridin-2-yl)-N(2)-(pyridin-2-ylmeth-yl)ethane-1,2-diamine (BPPPEN) ligand and two terminal chloride ligands, resulting in a highly distorted environment around the metal atom. The calculated τ parameter of 0.42 indicates that the coordination geometry is approximately square-pyramidal. Hydrogen bonds involving centrosymmetric N-H⋯Cl inter-actions form dimeric structures. The mol-ecules are stacked along the a and b axes.

Methyl 4-{[6-(4-bromo-phen-yl)-3-oxo-2,3,4,5-tetra-hydro-pyridazin-4-yl]methyl}benzoate.

The structure of the title compound, C(19)H(17)BrN(2)O(3), consists of two cyclic groups, viz. 4-(meth-oxy-carbon-yl)phenyl and 6-(4-bromo-phen-yl)-3-oxo-2,3,4,5-dihydro-pyridazin-4-yl, which are linked by a methyl-ene spacer. The pyridazine ring is twisted and the dihedral angle between its mean plane and that of the bromo-phenyl mean plane is 17.2 (2)°. The 4-(meth-oxy-carbon-yl)phenyl group shows a quasi-planar conformation, where the dihedral angle between the mean planes of the phenyl ring and carboxyl-ate ester group is 7.9 (4)°. Centrosymmetric inter-molecular N-H⋯O hydrogen bonds form dimers. These are linked by C-Br⋯O=C inter-actions [Br⋯O = 3.10 (1) Å] to form a one-dimensional polymeric structure running along the [1[Formula: see text]0] direction.

(3R,8aS)-3-Ethyl-perhydro-pyrrolo[1,2-a]pyrazine-1,4-dione.

In the title compound, C(9)H(14)N(2)O(2), the pyrrolidine and piperazine rings adopt envelope and boat conformations, respectively. The chiral centers were assigned on the basis of the known stereogenic center of an enanti-omerically pure starting material and the trans relationship between the H atoms attached to these centers. The crystal packing is stabilized by an inter-molecular hydrogen bond between the N-H group and a carbonyl O atom of the diketopiperazine group, forming zigzag C(5) chains along [010].

Leishmania amazonensis growth inhibitors: biological and theoretical features of sulfonamide 4-methoxychalcone derivatives.

Current drugs for treating leishmaniasis are still associated with significant toxicity and failure rates. Thus, new effective and less toxic antileishmanial agents are still in need. Herein, we tested a series of sulfonamide 4-methoxychalcone derivatives against L. amazonensis promastigote and amastigote forms to identify its antileishmanial profile against this species compared to L. braziliensis. In addition, we used molecular modeling tools to determine stereoelectronic features that may lead to the antileishmanial profile. Interestingly, all tested compounds were able to affect L. amazonensis promastigote form in a concentration-dependent manner and with low cytotoxicity, except for derivative 3g. However, our results showed that compound 3f (para-Cl) presents the best profile against both L. amazonensis forms (promastigote and amastigote), differently from that observed for L. braziliensis, when compound 3i was the most active. Structure-activity relationship (SAR) analysis of these derivatives pointed molecular volume, HOMO density, and conformational aspects as important characteristics for parasitic profile. Overall, sulfonamide 4-methoxychalcone derivatives may be pointed out not only as lead compounds for treating leishmaniasis (i.e., 3f) but also as experimental tools presenting parasite-selectivity (i.e., 3i).

Synthesis, biological evaluation and SAR of sulfonamide 4-methoxychalcone derivatives with potential antileishmanial activity.

Despite clinical importance of leishmaniasis, an infectious disease that affects 12 thousand million people in 88 countries, the treatment is still unsatisfactory due to its limited efficacy, cost expensive and undesirable side effects. Aiming to develop new antileishmanial lead compounds, we used a rational approach to synthesize a new set of sulfonamide 4-methoxychalcone derivatives (3a-3i) and evaluate the sulfonamide and methoxy moieties as promising adding-groups to chalcones. For that purpose we tested this new set against Leishmania braziliensis promastigotes and intracellular amastigotes and determined its cell toxicity profile. Interestingly all compounds presented a concentration-dependent antileishmanial profile and the benzylamino derivative (3i) showed a biological activity better than pentamidine. None of these compounds affected Trypanosoma cruzi epimastigotes, which suggests a specific antileishmanial profile. The structure-activity analysis of these sulfonamide 4-methoxychalcone derivatives pointed the molecular volume, the HOMO density concentrated in the chalcone moiety and the conformational structure of the compounds as important structural and stereoelectronic features for the antileishmanial activity. In addition, these compounds also fulfilled Lipinski rule of 5 and presented druglikeness similar to antileishmanial drugs. Altogether these results point the sulfonamide 4-methoxychalcone derivatives as potential lead compounds for designing new candidates for leishmaniasis treatment.

4,5,6,8,9-Pentachloropyrimido[1,2-a][1,8]naphthyridin-10-one.

The title compound, C11H2Cl5N3O, crystallizes in the monoclinic system with two molecules in the asymmetric unit. The molecules are chemically identical but have different structural parameters. In the three-dimensional packing, the molecules are arranged in dimers that are connected by slipped pi-pi stacking, and these dimers are connected to one another through several C-H...O and Cl...Cl interactions.