A copper-catalysed one-pot hydroboration/azidation/cycloaddition reaction of alkynes.

Herein we report our study on the development of a catalytic one-pot process, showing the challenges and advantages encountered all over the way. At the end, we developed a regioselective, environmentally friendly, and operationally simple method to explore the reactivity of functionalized propargylic alkynes through three copper-catalysed reactions in a single reaction vessel. The sequence consisted of a hydroboration, azidation, and 1,3-dipolar cycloaddition and led to the regioselective formation of vinyl 1,2,3-triazoles in good yields.

Identification and ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry characterization of biosurfactants, including a new surfactin, isolated from oil-contaminated environments.

Biosurfactant-producing bacteria were isolated from samples collected in areas contaminated with crude oil. The isolates were screened for biosurfactant production using qualitative drop-collapse test, oil-spreading and emulsification assays, and measurement of their tensoactive properties. Five isolates tested positive for in the screening experiments and displayed decrease in the surface tension below 30 mN m-1 . The biosurfactants produced by these isolates were further investigated and their molecular identification revealed that they are bacteria related to the Bacillus genus. Additionally, the biosurfactants produced were chemically characterized via UHPLC-HRMS experiments, indicating the production of surfactin homologues, including a new class of these molecules.

3-Hy-droxy-2-phenyl-2,3,3a,7a-tetra-hydro-1H,5H-pyrano[3,2-b]pyrrol-5-one: crystal structure and Hirshfeld surface analysis.

The title isoaltholactone derivative, C13H13NO3, has an NH group in place of the ether-O atom in the five-membered ring of the natural product. The five-membered ring is twisted about the N-C bond linking it to the six-membered ring, which has a half-chair conformation with the O atom connected to the ether-O atom lying above the plane defined by the remaining atoms. The dihedral angle between the mean planes of the rings comprising the fused-ring system is 75.10 (8)°. In the crystal, hy-droxy-O-H⋯N(amine) hydrogen bonding sustains linear supra-molecular chains along the a axis. Chains are linked into a three-dimensional architecture via amine-N-H⋯π(phen-yl) and phenyl-C-H⋯O(hy-droxy) inter-actions. The influence of the amine-N-H⋯π(phen-yl) contact on the mol-ecular packing is revealed by an analysis of the Hirshfeld surface.

Stereoselective Arylation of Amino Aldehydes: Overriding Natural Substrate Control through Chelation.

The chelation-controlled arylation reaction of chiral, enantiopure acyclic α-amino aldehydes enabled by a B/Zn exchange reaction between arylboronic acids and Et2Zn is reported. The presence of dibenzyl substituents at the nitrogen plays a key role in the stereochemical outcome of the reaction, and chelation is favored over the natural tendency of this type of substrate to undergo Felkin-Anh controlled additions with organomagnesium and organolithium reagents.

1,1,2-Tris-organoselenide alkene derivatives, but not 1,2-bis-organoselenide alkene derivatives, inhibited delta-aminolevulinate dehydratase activity from human erythrocytic cells in vitro.

Organochalcogens are important intermediates and useful reagents in organic synthesis. Recent data from our laboratory demonstrated that bis and tris-selenide alkene derivatives are attractive synthetic targets because of their chemio-, regio- and stereo-selective reactions. Since the erythrocytic delta-aminolevulinate dehydratase (delta-ALA-D) activity could be an important indicator of toxicity, this report investigated bis and tris-selenide alkene derivatives effects on blood delta-ALA-D in vitro. To investigate the mechanisms by which these compounds inhibit human blood delta-ALA-D activity, a thiol reducing agent or zinc chloride were used. 1,2-Bis-selenide alkene derivatives 1a (R=4-MeOC(6)H(4)), 1b (R=4-ClC(6)H(4)) and 1c (R=2,4,6-Me(3)C(6)H(2)) did not inhibit human blood delta-ALA-D activity. 1,1,2-Tris-selenide alkene derivative 2a (R=C(6)H(5)) was the most potent delta-ALA-D inhibitor. Compounds 2b (R=4-MeOC(6)H(4)) and 2c (R=4-ClC(6)H(4)) displayed similar inhibitory potency towards delta-ALA-D activity. Dithiothreitol, a hydrophobic SH-reducing agent, was able to restore and to protect delta-ALA-D activity inhibited by tris-selenide alkene derivatives. Conversely, ZnCl(2) did not alter the enzyme inhibition induced by tris-selenide alkene derivatives. From these findings we suggest that 1,1,2-tris-selenide alkene derivatives inhibited delta-ALA-D activity by an interaction with essential sulfhydryl groups for the enzyme activity.

Palladium-catalyzed Suzuki cross-coupling of 2-haloselenophenes: synthesis of 2-arylselenophenes, 2,5-diarylselenophenes, and 2-arylselenophenyl ketones.

We present herein our results on the Suzuki coupling reaction of 2-haloselenophenes with boronic acids catalyzed by palladium salt and describe a new route established to prepare 2-arylselenophenes and 2,5-diarylselenophenes in good yields. The reaction proceeded cleanly under mild conditions and was performed with aryl boronic acids bearing electron-withdrawing, electron-donating, and neutral substituents, in the presence of Pd(OAc)2, K2CO3/H2O in DME. In addition, by this protocol unsymmetrical aryl ketones were also obtained from 2-iodoselenophene and boronic acids via a carbonylative process.

Bis selenide alkene derivatives: A class of potential antioxidant and antinociceptive agents.

Bis and tris-selenide alkene derivatives, a class of organoselenium compounds, were screened for antinociceptive and antioxidant activities. In vitro, bis-selenide alkene 1c (R=2,4,6-Me(3)C(6)H(2)), 1d (R=4-ClC(6)H(4)) and 1e (R=4-MeOC(6)H(4)) protected against lipid peroxidation about 50%, whereas 1b (R=C(6)H(5)) and 1a (R=C(4)H(9)) protected only 23%. Compound 1d presented lesser IC(50) against lipid peroxidation than other bis-selenide alkene compounds (1d>1e> or =1c>1a=1b). The maximal inhibitory effect of tris-selenide alkenes on lipid peroxidation was in the following order 2c>2a=2b. Compound 1e increased the rate of GSH, but not DTT, oxidation. Tris-selenide alkene 2c (R=4-MeOC(6)H(4)) demonstrated the higher rate of thiol oxidation, while 2a (R=C(6)H(5)) did not change DTT oxidation but oxidized GSH. Conversely, compound 2b (R=4-ClC(6)H(4)) did not change the rate of GSH oxidation, but oxidized DDT. Bis-selenide alkene derivatives 1c, 1d and 1e were the most promising compounds tested in vitro. In vivo, compounds 1c and 1d (5-50mg/kg, subcutaneously) produced significant inhibition of acetic acid- and capsaicin-induced pain. Compounds 1c and 1d increased the tail-flick response latency time. The antinociception effect of 1c and 1d was not abolished by naloxone (an antagonist of opioid receptor, 1mg/kg, subcutaneously), suggesting that the antinociceptive effect is not influenced by the opioidergic mechanism.