Microwave-promoted Suzuki coupling reactions with organotrifluoroborates in water using ultra-low catalyst loadings

The Suzuki reaction in water using parts per million concentrations of palladium is reported using potassium trifluoroborates as alternatives to boronic acids as substrates.     

Investigation of the surfactant type and concentration effect on the retention factors of glutathione and its analogues by micellar electrokinetic chromatography

In the present study, a micellar electrokinetic chromatographic method was used to determine the retention factors of hydrophilic monomeric and homodimeric forms of glutathione analogues. Ionic‐liquid‐based surfactant, 1‐tetradecyl‐3‐methylimidazolium chloride, as well as cetyltrimethylammonium bromide and phosphate buffer (pH 7.4) were employed in the experiments. Since the studied peptides possess a negative charge under physiological conditions, it is expected that the peptides interact with the oppositely charged 1‐tetradecyl‐3‐methylimidazolium chloride and cetyltrimethylammonium bromide micelles via hydrophobically assisted electrostatic forces. The dependence of the retention factor on the micellar concentration of 1‐tetradecyl‐3‐methylimidazolium chloride and cetyltrimethylammonium bromide is nonlinear and the obtained curves converge to a limiting value. The retention factor values of GSH analogues were in the range of 0.36–2.22 for glutathione analogues and –1.21 to 0.37 for glutathione when 1‐tetradecyl‐3‐methylimidazolium chloride was used. When cetyltrimethylammonium bromide was employed, the retention factor values were in the range of 0.27–2.17 for glutathione analogues and –1.22 to 0.06 for glutathione. If sodium dodecyl sulfate was used, the retention factor values of glutathione analogues with carnosine moiety were in the range of –1.54 to 0.38.     

7‐(2‐Oxoalkoxy)coumarins: Synthesis and Anti‐Inflammatory Activity of a Series of Substituted Coumarins

A series of 7‐(2‐oxoalkoxy)coumarins have been synthesized by conjugating substituted 7‐hydroxycoumarins with different chloroketones. The anti‐inflammatory properties of 7‐(2‐oxoalkoxy)coumarins were studied in LPS‐induced inflammatory response in J774 macrophages. Western blot was used to determine the expression of iNOS and COX‐2, NO was determined by measuring its metabolite nitrite by Griess reaction and IL‐6 was measured by ELISA. Seventeen of the studied compounds inhibited NO and IL‐6 production over 50% at 100 μM concentrations. IC₅₀ values of the best inhibitors were 21 μM/24 μM (NO/IL‐6) for compound 12 and 30 μM/10 μM (NO/IL‐6) for compound 20 . The main result was that the substitution with 7‐(2‐oxoalkoxy) group improved the anti‐inflammatory properties of most of the investigated 7‐hydroxycoumarins.     

A reassessment of the transition-metal free suzuki-type coupling methodology

We present here a reassessment of our transition-metal free Suzuki-type coupling protocol. We believe that, although the reaction can be run without the need for addition of a metal catalyst, palladium contaminants down to a level of 50 ppb found in commercially available sodium carbonate are responsible for the generation of the biaryl rather than, as previously suggested, an alternative non-palladium-mediated pathway. We present a revised methodology for Suzuki couplings using ultralow palladium concentrations for use with aryl and vinyl boronic acids and discuss the effects of the purity of the boronic acid on the reaction.     

Automated batch scale-up of microwave-promoted Suzuki and Heck coupling reactions in water using ultra-low metal catalyst concentrations

Representative Suzuki and Heck couplings in water using ultra-low catalyst concentrations have been scaled-up using an automated batch stop-flow microwave apparatus. Our scale-up methodology shows proof of concept and is easy, fast and cheap to run.     

Size‐Control by Anion Templating in Mechanochemical Synthesis of Hemicucurbiturils in the Solid State

Self‐organization is one of the most intriguing phenomena of chemical matter. While the self‐assembly of macrocycles and cages in dilute solutions has been extensively studied, it remains poorly understood in solvent‐free environments. Provided here is the first example of using anionic templates to achieve selective assembly of differently‐sized macrocycles in a solvent‐free system. Using acid‐catalyzed synthesis of cyclohexanohemicucurbiturils as a model, size‐controlled, quantitative synthesis of 6‐ or 8‐membered macrocycles by spontaneous anion‐directed reorganization of mechanochemically‐made oligomers in the solid state is demonstrated.     

Characterization of the antioxidative activity of novel nontoxic neuropeptides by using capillary electrophoresis

In the present study, we have monitored the oxidation process of novel nontoxic neuropeptides and determined its rate constants, which describe the antioxidative potential of the peptides. A capillary electrophoretic method was implemented which ensures the simultaneity of analysis of reactants and products in a short time of analysis. The rate constants of oxidation of the four novel peptides, 4-methoxy-L-tyrosinyl-gamma-L-glutamyl-L-cysteinyl-glycine (UPF1), D-serinyl-gamma-L-glutamyl-L-cysteinyl-glycine (UPF6), 4-methoxy-L-tyrosinyl-alpha-L-glutamyl-L-cysteinyl-glycine and D-serinyl-alpha-L-glutamyl-L-cysteinyl-glycine, designed by us, were compared with those of oxidation of glutathione (reduced glutathione) by using capillary electrophoresis. The second-order rate constants were similar for all peptides if the oxidation was carried out with hydrogen peroxide (k(II) = 0.208 - 0.236 x 10(3)/M.min). The rate constants were also determined for the mixtures of peptides. When the oxidation is caused by hydroxyl radical (OH*), the gamma-glutamate containing peptides (UPF1 and UPF6) exhibited two to four times higher antioxidative activity (k(II) = 4.428 and 2.152 x 10(3)/M.min, respectively). The results suggest that the antioxidative potential of the peptides studied is not determined by the formation of disulphide bridge alone.     

Rapid cyanation of aryl iodides in water using microwave promotion

We show that using water in conjunction with microwave heating it is possible to prepare aryl nitriles from the corresponding aryl iodides rapidly and in high yield without the need for a palladium catalyst.     

Rapid, easy cyanation of aryl bromides and chlorides using nickel salts in conjunction with microwave promotion

We report here a fast, easy, and efficient method for the preparation of aryl nitriles from aryl bromides and chlorides. The methodology for aryl bromides involves the use of either Ni(CN)(2) or NaCN and NiBr(2). With aryl chlorides, a mix of NaCN and NiBr(2) is used and the reaction proceeds via the in situ formation of the corresponding aryl bromide. The reaction can be performed in air and is complete within 10 min.