Ricardo S. Schwab

Highly Efficient and Magnetically Recoverable Niobium Nanocatalyst for the Multicomponent Biginelli Reaction

A new magnetically recoverable nanocatalyst was prepared by coating magnetite with niobium oxide (Fe3O4@Nb2O5) by using a simple wet impregnation method. The Fe3O4@Nb2O5 nanocatalyst was fully characterized, and its catalytic activity was evaluated by using the one‐pot, three‐component Biginelli reaction, with the aim to synthesize 1,4‐dihydropyrimidinones, a class of compounds with diverse pharmacological properties. The developed protocol was applied to a wide range of aliphatic and aromatic substrates, and structurally diverse products were obtained in excellent yields. Compared with copper and nickel nanocatalysts, the Fe3O4@Nb2O5 nanocatalyst demonstrated superior catalytic activity at a remarkably low catalyst loading (0.1u2005molu2009%). This niobium nanocatalyst could be easily separated from the reaction mixture with an external magnet and was reused several times without any loss of its catalytic activity. Moreover, although the Biginelli reaction is a century‐old reaction, its mechanism is still a controversial subject, and our investigation provided an insight into the reaction mechanism.

CuO nano particles and [bmim]BF4: an application towards the synthesis of chiral β-seleno amino derivatives via ring opening reaction of aziridines with diorganyl diselenides

A series of chiral β-seleno amino derivatives were synthesized via a ring opening reaction of different aziridines with diorganyl diselenides mediated by recyclable CuO nanopowder and an ionic liquid affording the corresponding products in good to excellent yields. The [bmim]BF4 ionic liquid acts as both promoter and reaction medium. Compared to the usual organic solvents the ionic liquid exhibited better performance with the advantage of its recyclability.

Anxiolytic effects of diphenyl diselenide on adult zebrafish in a novelty paradigm

Anxiety-related disorders are frequently observed in the population. Because the available pharmacotherapies for anxiety can cause side effects, new anxiolytic compounds have been screened using behavioral tasks. For example, diphenyl diselenide (PhSe)2, a simple organoselenium compound with neuroprotective effects, has demonstrated anxiolytic effects in rodents. However, this compound has not yet been tested in a novelty-based paradigm in non-mammalian animal models. In this study, we assessed the potential anxiolytic effects of (PhSe)2 on the behavior of adult zebrafish under novelty-induced stress. The animals were pretreated with 0.1, 0.25, 0.5, and 1μM (PhSe)2 in the aquarium water for 30min. The fish were then exposed to a novel tank, and their behavior was quantified during a 6-min trial. (PhSe)2 treatment altered fish behavior in a concentration-dependent manner. At 0.01 and 0.25μM, (PhSe)2 did not elicit effects on fish behavior. At 0.5μM, moderate behavioral side effects (e.g., lethargy and short episodic immobility) were noted. At the highest concentration tested (1μM), dramatic side effects were observed, such as burst behavior and longer periods of immobility. The results were confirmed by spatiotemporal analysis of each group. Occupancy plot data showed dispersed homebase formation in the 0.25μM (PhSe)2-treated group compared with the control group (treated with 0.04% DMSO). Furthermore, animals treated with 0.25μM (PhSe)2 showed a reduction in latency to enter the top and spent more time in the upper area of the tank. These data suggest that (PhSe)2 may induce an anxiolytic-like effect in situations of anxiety evoked by novelty.