Diamidocarbenes as versatile and reversible [2+1] cycloaddition reagents

We describe the synthesis of a variety of cyclopropanes and epoxides by combining a readily accessible and isolable N,N-2-diamidocarbene with a range of structurally and electronically diverse olefins and aldehydes, including electron-rich derivatives. Surprisingly, the cyclopropanation and epoxidation reactions were discovered to be rapid and thermally reversible at relatively low temperatures, two features often desired for applications that utilize dynamic covalent chemistry. In addition, a diamidocyclopropane derivative prepared via this method was hydrolysed successfully to form the corresponding linear carboxylic acid in a metal-and carbon monoxide-free hydrocarboxylation reaction. As such, diamidocarbenes are expected to find utility in the synthesis of cyclopropanes, epoxides and their derivatives, as well as in dynamic covalent chemistry applications.close424

Dynamic multi-component covalent assembly for the reversible binding of secondary alcohols and chirality sensing

Reversible covalent bonding is often employed for the creation of novel supramolecular structures, multi-component assemblies, and sensing ensembles. In spite of remarkable success of dynamic covalent systems, the reversible binding of a mono-alcohol with high strength is challenging. Here we show that a strategy of carbonyl activation and hemiaminal ether stabilization can be embodied in a four-component reversible assembly that creates a tetradentate ligand and incorporates secondary alcohols with exceptionally high affinity. Evidence is presented that the intermediate leading to binding and exchange of alcohols is an iminium ion. Further, to demonstrate the use of this assembly process we explored chirality sensing and enantiomeric excess determinations. An induced twist in the ligand by a chiral mono-ol results in large Cotton effects in the circular dichroism spectra indicative of the alcohol’s handedness. The strategy revealed in this study should prove broadly applicable for the incorporation of alcohols into supramolecular architecture construction

A literature review of the pharmacokinetics and pharmacodynamics of dobutamine in neonates

Since its discovery in 1975 dobutamine has been used off-label for treating hemodynamic insufficiency in newborns and children. We present a structured literature review of pharmacokinetic and pharmacodynamic data for dobutamine in the pediatric population. Structured searches were conducted to identify relevant articles according to pre-defined inclusion criteria. Where possible, results for the pharmacodynamic and pharmacokinetic effect of dobutamine were reported as pooled data. Fortysix papers met the inclusion criteria. With regard to pharmacodynamic data a number of studies reported significant increases in a number of clinical parameters such as heart rate, blood pressure, cardiac output across a wide range of pediatric populations. With regard to pharmacokinetic data studies reported that the infusion rate was positively correlated to plasma dobutamine concentration. There was great variability with regard to dobutamine clearance between individuals and as to whether it followed first- or zero-order elimination kinetics. While the pharmacodynamic effects of dobutamine appear to reflect the pharmacological profile of the drug, the pharmacokinetic data are difficult to interpret due to inhomogeneity between study populations ages, comorbidities, dobutamine dosages and methodologies. High-quality prospective pharmacokinetic and pharmacodynamic data especially in newborns are urgently required prior to a large randomized study