Utilization of a kinetic isotope effect to decrease decomposition of ceftriaxone in a mixture of DO/HO.

The discovery of cephalosporin and demonstration of its improved stability in aqueous solution, as well as enhanced in vitro activity against penicillin-resistant organisms, were major breakthroughs in the development of β-lactam antibiotics. Although cephalosporins are more stable with respect to hydrolytic degradation than penicillins, they still experience a variety of chemical transformations. The present study offers an insight into the rates and mechanisms of ceftriaxone degradation at the therapeutic concentration in water, a mixture of water and deuterium oxide, and deuterium oxide itself at the neutral pH.

Epimeric Face-Selective Oxidations and Diastereodivergent Transannular Oxonium Ion Formation Fragmentations: Computational Modeling and Total Syntheses of 12-Epoxyobtusallene IV, 12-Epoxyobtusallene II, Obtusallene X, Marilzabicycloallene C, and Marilzabicycloallene D.

The total syntheses of 12-epoxyobtusallene IV, 12-epoxyobtusallene II, obtusallene X, marilzabicycloallene C, and marilzabicycloallene D as halogenated C-acetogenin 12-membered bicyclic and tricyclic ether bromoallene-containing marine metabolites from Laurencia species are described. Two enantiomerically pure C-epimeric dioxabicyclo[8.2.

Kinetic and computational studies on Pd(I) dimer-mediated halogen exchange of aryl iodides.

Building on our previous discovery and reactivity explorations of the Pd(I) dimer [(PtBu3)PdBr]2-mediated halogen exchange of aryl iodides [Chem. Sci. 2013, 4, 4434], this report presents kinetic studies of this process, giving first-order kinetic dependence in the Pd(I) dimer and aryl iodide.

Computational ligand design for the reductive elimination of ArCF₃ from a small bite angle Pd(II) complex: remarkable effect of a perfluoroalkyl phosphine.

To date only three ligands are known to trigger the challenging reductive elimination of ArCF3 from Pd(II). We report the computational design of a bidentate trifluoromethylphosphine ligand that although exhibiting a generally ineffective small bite angle is predicted to give facile reductive elimination. Our experimental verification gave quantitative formation of ArCF3 at 80 °C within 2 h.

Experiment and computation: a combined approach to study the reactivity of palladium complexes in oxidation states 0 to IV.

As the accuracy of computational chemistry increases, and the advent of more powerful computers decreases the amount of time required to perform complex calculations, the use of this to investigate chemical systems becomes increasingly attractive. Particularly in combination with practical lab-based experimental and spectroscopic studies the application of in silico studies is a powerful tool for mechanistic investigations. In this review we demonstrate how a combined experimental and computational approach can yield mechanistic insight that could frequently not have been accessible to this high degree of certainty by utilising one of these two approaches alone.

Trifluoromethylation of ketones and aldehydes with Bu₃SnCF₃.

The (trifluoromethyl)stannane reagent, Bu3SnCF3, was found to react under CsF activation with ketones and aldehydes to the corresponding trifluoromethylated stannane ether intermediates at room temperature in high yield. Only a mildly acidic extraction (aqueous NH4Cl) is required to release the corresponding trifluoromethyl alcohol products. The protocol is compatible with acid-sensitive functional groups.

A unifying stereochemical analysis for the formation of halogenated C15-acetogenin medium-ring ethers from Laurencia species via intramolecular bromonium ion assisted epoxide ring-opening and experimental corroboration with a model epoxide.

A unifying stereochemical analysis for the formation of the constitutional isomeric halogenated C(15)-acetogenin medium-ring ether natural products from Laurencia species is presented, where an intramolecular bromonium ion assisted epoxide ring-opening reaction of enantiomerically pure epoxides can account for ring-size, the position of the halogen substituents, and relative and absolute configurations of the known natural products. Experimentally, a model epoxide corroborates the feasibility of this process for concurrent formation of 7-, 8- and 9-ring ethers corresponding to the halogenated medium-ring ethers of known metabolites from Laurencia species.

Intramolecular bromonium ion assisted epoxide ring-opening: capture of the oxonium ion with an added external nucleophile.

9-Oxabicyclo[6.1.0]non-4-ene (1) undergoes intramolecular bromonium ion-assisted epoxide ring-opening using N-bromosuccinimide via a presumed oxonium ion that is subject to stereospecific, nonregioselective capture with added external nucleophiles producing novel bicyclo[4.