Mechanism of C-3 Acyl Neighboring Group Participation in Mannuronic Acid Glycosyl Donors.

One of the main challenges in oligosaccharide synthesis is the stereoselective introduction of the glycosidic bond. In order to understand and control glycosylation reactions, thorough mechanistic studies are required. Reaction intermediates found by NMR spectroscopy often cannot explain the glycosylation's stereochemical outcome.

Characterization of elusive rhamnosyl dioxanium ions and their application in complex oligosaccharide synthesis.

Attaining complete anomeric control is still one of the biggest challenges in carbohydrate chemistry. Glycosyl cations such as oxocarbenium and dioxanium ions are key intermediates of glycosylation reactions. Characterizing these highly-reactive intermediates and understanding their glycosylation mechanisms are essential to the stereoselective synthesis of complex carbohydrates.

Detection and Characterization of Rapidly Equilibrating Glycosylation Reaction Intermediates Using Exchange NMR.

The stereoselective introduction of glycosidic bonds (glycosylation) is one of the main challenges in the chemical synthesis of carbohydrates. Glycosylation reaction mechanisms are difficult to control because, in many cases, the exact reactive species driving product formation cannot be detected and the product outcome cannot be explained by the primary reaction intermediate observed. In these cases, reactions are expected to take place via other low-abundance reaction intermediates that are in rapid equilibrium with the primary reaction intermediate via a Curtin-Hammett scenario.

Changes in QRS duration are associated with maximal exercise capacity in adult patients with repaired tetralogy of Fallot.

Objective: In adult patients with repaired tetralogy of Fallot (TF) QRS duration at rest seems to be a predictor of maximal exercise. We examined the relationship between QRS duration during exercise and exercise performance.

Design: In 57 consecutive TF patients QRS duration in V1 (ms) was measured at rest, at maximal exercise (Wmax, W), and at peak oxygen consumption (peak VO2, ml/min).