Tellurium in organic synthesis: a new approach to trisubstituted gamma-butyrolactones with trans-trans relative stereochemistry. Total enantioselective synthesis of (-)-Blastmycinolactol, (+)-Blastmycinone, (-)-NFX-2, and (+)-Antimycinone

The total synthesis of (-)-Blastmycinolactol, (+)-Blastmycinone, (-)-NFX-2, and (+)-Antimycinone was accomplished in few steps in high yields and ee, starting from enantiomerically enriched (S)-Z-vinylic hydroxytellurides. (C) 2010 Published by Elsevier Ltd.

A Diastereoselective Total Synthesis of trans-Trikentrin A: A Ring Contraction Approach

A new route to obtain the polyalkylated indole (+/-)-trans-trikentrin A was developed. The synthesis of this natural alkaloid features a thallium(III)mediated ring contraction reaction to obtain the trans-1,3-disubstituted five-membered ring in a diastereoselective manner. Thallium(III) is chemoselective in this rearrangement, reacting with the olefin without oxidation of the indole moiety. Other key transformations are the Bartoli`s reaction to construct the heterocyclic ring and a Heck coupling to add the carbons atom that will originate the nonaromatic cycle.

Study of a gold electrode modified by trans-[Ru(NH(3))(4)(Ist)SO(4)](+) to produce an electrochemical sensor for nitric oxide

The modification of a gold electrode surface by electropolymerization of trans-[Ru(NH(3))(4)(Ist)SO(4)](+) to produce an electrochemical sensor for nitric oxide was investigated. The influence of dopamine, serotonin and nitrite as interferents for NO detection was also examined using square-wave voltammetry (SWV). The characterization of the modified electrode was carried out by cyclic voltammetry, electrochemical quartz crystal microbalance (EQCM) and SERS techniques. The gold electrode was successfully modified by the trans-[Ru(NH(3))(4)(Ist)SO(4)](+) complex ion using cyclic voltammetry. The experiments show that a monolayer of the film is achieved after ten voltammetric cycles, that NO in solution can coordinate to the metal present in the layer, that dopamine, serotonin and nitrite are interferents for the detection of NO, and that the response for the nitrite is much less significant than the responses for dopamine and serotonin. The proposed modified electrode has the potential to be applied as a sensor for NO. (C) 2011 Elsevier Ltd. All rights reserved.

Synthesis, spectral studies and X-ray crystal structure of N,N `-(+/-)-trans-1,2-cyclohexylenebis(3-ethoxysalicylideneamine) H-2(t-3-EtOsalchxn)

The synthesis, spectra and X-ray crystal structure of N,N`-(+/-)-trans-1,2-cyclohexylenebis(3-ethoxysalicylideneamine) H-2(t-3-EtOsalchxn), a salen-type ligand, are reported. The Schiff base was characterized by elemental analysis, m.p., IR, electronic spectra, H-1 and C-13 NMR spectra. The spectra are discussed and compared with those of N,N`-(+/-)-trans-1,2-cyclohexylenebis(salicylideneamine), H-2(t-salchxn). The electronic and IR spectra were also resolved by deconvolution. The influence of the ethoxy group on the IR, electronic spectrum, H-1 and C-13 NMR spectra is discussed. Strong intramolecular forces are present as supported by the IR and H-1 NMR spectra and the X-ray crystal structure. An intermolecular hydrogen bond is observed and appears twice in a pair of molecules in the unit cell. (c) 2007 Elsevier B.V. All rights reserved.

Towards to the trans-bromination of 2-styrylpyridine with a palladacycle intermediary and structure analysis for trans-1,2-dibromo-2-styrylpyridine

The simple halogenation of alkynes in conventional organic reactions gives a blend of cis and trans isomers. It is proposed then, a synthesis of stereospecific halogenation of alkynes in trans position, using palladacycle as intermediaries. The recrystallization of the compound obtained by bromination of 2-Styrylpyridine, with cyclepalladium intermediary results in a single crystal, which is subjected to X-ray diffraction. The crystal packing is established through weak interactions of three types. The first one is of the type pi x pi interactions, from symmetry operation, between the centroids. The second one is of the type C-X center dot center dot center dot pi interactions. And the last type is an anomalous intermolecular interaction between halogens, C-X center dot center dot center dot X-C, with bond distances smaller than the sum of the van der Waals radii. The conformation on the C=C bond is trans and the dihedral angle between the aromatic rings is (with esd approximate) 18.1(3)degrees. (C) 2010 Elsevier B.V. All rights reserved.

Experimental Chemotherapy against Trypanosoma cruzi Infection Using Ruthenium Nitric Oxide Donors

The ruthenium NO donors of the group trans-[Ru(NO)(NH(3))(4)L](n+), where the ligand (L) is N-heterocyclic H(2)O, SO(3)(2 -), or triethyl phosphite, are able to lyse Trypanosoma cruzi in vitro and in vivo. Using half-maximal (50%) inhibitory concentrations against bloodstream trypomastigotes (IC(50)(try)) and cytotoxicity data on mammalian V-79 cells (IC(50)(V79)), the in vitro therapeutic indices (TIs) (IC(50)(V79)/IC(50)(try)) for these compounds were calculated. Compounds that exhibited an in vitro TI of >= 10 and trypanocidal activity against both epimastigotes and trypomastigotes with an IC(50)(try/epi) of <= 100 mu M were assayed in a mouse model for acute Chagas` disease, using two different routes (intraperitoneal and oral) for drug administration. A dose-effect relationship was observed, and from that, the ideal dose of 400 nmol/kg of body weight for both trans-[Ru(NO)(NH(3))(4)isn](BF(4))(3) (isn, isonicotinamide) and trans-[Ru(NO)(NH3) 4imN](BF4) 3 (imN, imidazole) and median (50%) effective doses (ED50) of 86 and 190 nmol/kg, respectively, were then calculated. Since the 50% lethal doses (LD(50)) for both compounds are higher than 125 mu mol/kg, the in vivo TIs (LD(50)/ED(50)) of the compounds are 1,453 for trans-[Ru(NO)(NH(3))(4)isn](BF(4))(3) and 658 for trans-[Ru(NO)(NH(3))(4)imN](BF(4))(3). Although these compounds exhibit a marked trypanocidal activity and are able to react with cysteine, they exhibit very low activity in T. cruzi -glycosomal glyceraldehyde-3-phosphate dehydrogenase tests, suggesting that this enzyme is not their target. The trans-[Ru(NO)(NH(3))(4)isn](BF(4))(3) and trans-[Ru(NO)(NH(3))(4)imN](BF(4))(3) compounds are able to eliminate amastigote nests in myocardium tissue at 400-nmol/kg doses and ensure the survival of all infected mice, thus opening a novel set of therapies to try against trypanosomatids.

Effects of melatonin on hemolymph glucose and lactate concentrations in the fiddler crab, uca pugilator

Melatonin (N-acetyl-5-methoxytryptamine) is an indolamine hormone produced by the pineal gland that works to regulate sleep/wake cycles and activity rhythms. The effects of melatonin in metabolism are far from understood. Melatonin was injected into the fiddler crab, Uca pugilator, to investigate the effects of melatonin on hemolymph glucose and lactate levels. Following injection at t=O, hemolymph samples were collected at t=O.5, 1.0, 1.5 and 5.0 hours. Melatonin caused a decrease in the stress response to injection and also caused delayed hyperglycemia. Melatonin-injected crabs also retained the glucose and lactate rhythymicity when compared to saline-injected crabs. Glucose and lactate rhythms followed the same pattern indicating that the cycles are coupled. Also, melatonin was synthesized using tbe Fischer Indole synthesis and characterized using H?NMR. The synthetic melatonin demonstrated biological activity when injected into the crabs as when compared to pure melatonin on the effects on glucose and lactate concentrations. Overall, melatonin influences both glucose metabolism and the production of lactate.

Synthesis of 2-oxo-16-(3', 4'-methylenedioxyphenyl)-trans-15-hexadecene

This work presents the progress made towards synthesizing 2-oxo-16-(3', 4'methylenedioxyphenyl)-trans-15-hexadecene, an antimycobacterial compound that was originally isolated from the leaves of Piper Sanctum. The hydrocarbon chain of the molecule was synthesized first by opening a 15-pentadecanolactone ring by means of HI, and performing an E2 elimination reaction on the molecule followed by an organolithium reaction with CH3Li. Hexadec-15-en-2-one that was afforded this way was later reacted with 5-bromobenzo[d][1,3]dioxole following the appropriate Heck reaction protocol that allows for the formation of a palladium catalyzed carbon-carbon bond. The modes of action of 2-oxo-16-(3', 4'-methylenedioxyphenyl)-trans-15hexadecene are comparable to the ones of rifampicin, a marketable drug that has been successfully used in the treatment of tuberculosis in the past. Additionally, this compound can serve as an intermediate towards the synthesis of 2-oxo-16-(3', 4' methylenedioxyphenyl)-hexadecane and 2-oxo-14-(3', 4' -methylenedioxyphenyl) tetradecane, both strong inhibitors of the growth of Mycobacterium tuberculosis. Lastly, due to Multi-Drug Resistant tuberculosis, there has been an increasing need to find alternative cures for tuberculosis. Therefore, the work on 2-qxo-16-(3', 4'methylenedioxyphenyl)-trans-15-hexadecene is not only chemically interesting but it is also biologically important.