Ignacio Carrera

Toluene Dioxygenase-Catalysed Oxidation of Benzyl Azide to Benzonitrile: Mechanistic Insights for an Unprecedented Enzymatic Transformation.

Enzymatic dioxygenation of benzyl azide by toluene dioxygenase (TDO) produces significant amounts of the cis‐cyclohexadienediol derived from benzonitrile, along with the expected azido diols. We demonstrate that TDO catalyses the oxidation of benzyl azide to benzonitrile, which is further dioxygenated to produce the observed cis‐diol. A proposed mechanism for this transformation involves initial benzylic monooxygenation followed by a nitrene‐mediated rearrangement to form an oxime, which is further dehydrated to afford the nitrile. To the best of our knowledge, this is the first report of enzymatic oxidation of an alkyl azide to a nitrile. In addition, the described oxime‐dehydration activity has not been reported for Rieske dioxygenases.

New polynuclear compounds based on N-benzyliminodipropionic acid: solution studies, synthesis, and X-ray crystal structures

Abstract Three new polynuclear compounds based on a dicarboxylic acid ligand are reported. In particular, two Cu(II) coordination compounds, [Cu2(H2O)6(Hbzlidp)2](CF3SO3)2·2H2O (1) and [Cu(NO3)(Hbzlidp)]∞ (2) (bzlidp2− = N-benzyliminodipropionate anion), and a Ni(II) dinuclear compound, [Ni2(H2O)4(bzlidp)2] (3), were synthesized and characterized by IR spectroscopy, elemental analysis and single crystal X-ray diffraction. Different structures were obtained depending on the reaction conditions. The structural analyses reveal that 1 was formed by dinuclear [Cu2(H2O)6(Hbzlidp)2]2+ units built by two copper(II) ions joined through two Hbzlidp− ligands, while 2 was formed by pairs of Cu(II) centers bridged by four syn,syn carboxylate groups to generate “paddle wheel” units. The dinuclear copper units are arranged in a rhombus type grid, in a 2-D layer structure. In both cases, the N was protonated and not coordinated to the metal center. Compound 3 was formed by [Ni2(H2O)4(bzlidp)2] neutral dinuclear units, with octahedral Ni(II) centers. Solution studies of the ligand–M(II) systems (M(II) = Mn, Co, Ni, Cu, Zn, Cd, and Pb) were also carried out.

Synthesis and field evaluation of synthetic blends of the sex pheromone of Crocidosema aporema (Lepidoptera: Tortricidae) in soybean

Crocidosema (= Epinotia) aporema (Walsingham) (Lepidoptera: Tortricidae) is a bud borer that feeds on soybean and forage legumes. Its economic importance is restricted to South America, where it can alternate throughout the year between forage and grain legumes. The sex pheromone of C. aporema females is composed of a 15:1 mixture of (7Z,9Z)-dodeca-7,9-dien-1-ol and (7Z,9Z)-dodeca-7,9-dienyl acetate. Aiming at the development of a monitoring tool, it was synthesized both components of the pheromone and evaluated male captures in pheromone traps baited with different blends of synthetic pheromone, in an experimental soybean field in Uruguay. The conjugated dienes were obtained from 2-pentyn-1-ol and 1,7-heptanediol, by oxidation of the former, Wittig coupling and Zn-catalyzed reduction of the triple bond. The 1:1 mixture was the most efficient in capturing males. The pheromone traps were attractive for up to 40 days, even with small septum loads (0.1 mg) and low population levels.

A Zn(II) luminescent complex with a Schiff base ligand: solution, computational and solid state studies

Abstract A new mononuclear complex of zinc(II), [Zn(HL)2]∙2DMF (H2L = (E)-N′-((E)-(hydroxyimino)butan-2-ylidene)salicyloylhydrazide, DMF = N,N-dimethylformamide), was prepared and characterized. Single-crystal X-ray crystallography revealed a six-coordinate zinc(II) surrounded by nitrogen of the oxime function and oxygen and distal nitrogens of the acylhydrazone group. This entity also exists in solution as demonstrated by 1H-NMR and potentiometric titrations. The computational analysis showed that the molecular orbitals involved in the main electronic transitions of the complex species in solution are centered on the ligand with negligible contribution of the metal ion. The photophysical properties of the complex were evaluated in solution and in the solid state. Luminescence studies showed that the solid has a strong emission at 550 nm with a large Stokes shift with respect to absorption. The solid state fluorescence emission is ascribed to ligand-centered and/or ligand-to-ligand charge transfer transitions, following the DFT results in solution. A comparison with a previously reported mononuclear [Zn(HL)2] allowed the investigation of the influence of DMF molecules in the structural packing and the luminescence properties.

Ibogaine Acute Administration in Rats Promotes Wakefulness, Long-Lasting REM Sleep Suppression, and a Distinctive Motor Profile

Ibogaine is a potent psychedelic alkaloid that has been the focus of intense research because of its intriguing anti-addictive properties. According to anecdotic reports, ibogaine has been originally classified as an oneirogenic psychedelic; i.e., induces a dream-like cognitive activity while awake. However, the effects of ibogaine administration on wakefulness (W) and sleep have not been thoroughly assessed. The main aim of our study was to characterize the acute effects of ibogaine administration on W and sleep. For this purpose, polysomnographic recordings on chronically prepared rats were performed in the light phase during 6 h. Animals were treated with ibogaine (20 and 40 mg/kg) or vehicle, immediately before the beginning of the recordings. Furthermore, in order to evaluate associated motor behaviors during the W period, a different group of animals was tested for 2 h after ibogaine treatment on an open field with video-tracking software. Compared to control, animals treated with ibogaine showed an increase in time spent in W. This effect was accompanied by a decrease in slow wave sleep (SWS) and rapid-eye movements (REM) sleep time. REM sleep latency was significantly increased in animals treated with the higher ibogaine dose. While the effects on W and SWS were observed during the first 2 h of recordings, the decrement in REM sleep time was observed throughout the recording time. Accordingly, ibogaine treatment with the lower dose promoted an increase on locomotion, while tremor and flat body posture were observed only with the higher dose in a time-dependent manner. In contrast, head shake response, a behavior which has been associated in rats with the 5HT2A receptor activation by hallucinogens, was not modified. We conclude that ibogaine promotes a waking state that is accompanied by a robust and long-lasting REM sleep suppression. In addition, it produces a dose-dependent unusual motor profile along with other serotonin-related behaviors. Since ibogaine is metabolized to produce noribogaine, further experiments are needed to elucidate if the metabolite and/or the parent drug produced these effects.