Direct Experimental Characterization of a Sialyl Cation.

Sialic acids are monosaccharide residues involved in several biological processes. Controlling the stereoselectivity of sialylation reactions is challenging and mechanistic studies on the structure of its intermediate, the sialyl cation, are scarce. Here it is shown that a sialyl cation can be generated and isolated from an ionized sialic acid precursor.

Location, Location, Location: Establishing Design Principles for New Antibacterials from Ferric Siderophore Transport Systems.

This review strives to assemble a set of molecular design principles that enables the delivery of antibiotic warheads to Gram-negative bacterial targets (ESKAPE pathogens) using iron-chelating siderophores, known as the Trojan Horse strategy for antibiotic development. Principles are derived along two main lines. First, archetypical siderophores and their conjugates are used as case studies for native iron transport.

Does size matter? - Comparing pyranoses with septanoses as ligands of the bacterial lectin FimH.

The pharmacological modulation of disease-relevant carbohydrate-protein interactions represents an underexplored area of medicinal chemistry. One particular challenge in the design of glycomimetic compounds is the inherent instability of the glycosidic bond toward enzymatic cleavage. This problem has traditionally been approached by employing S-, N-, or C-glycosides with reduced susceptibility toward glycosidases.

Characterization and Fate of a Septanosyl Ferrier Cation in the Gas and Solution Phases.

Ferrier reactions follow a mechanistic pathway whereby Lewis acid activation of a cyclic enol ether facilitates departure of an allylic leaving group to form a glycosyl Ferrier cation. Attack on the Ferrier cation provides a new acetal linkage concurrent with the transposition of the alkene moiety. The idiosyncratic outcomes of Ferrier reactions of seven-membered ring carbohydrate-based oxepines prompted an investigation of its corresponding septanosyl Ferrier cation.

Synthesis and Characterization of Preacinetobactin and 5-Phenyl Preacinetobactin.

We report the first total synthesis of 5-phenyl preacinetobactin and its characterization. The route was developed for the synthesis of preacinetobactin, the siderophore critical to the Gram-negative pathogen . It leverages a C5-substituted benzaldehyde as a key starting material and should enable the synthesis of similar analogs.