Continuous-flow synthesis of highly functionalized imidazo-oxadiazoles facilitated by microfluidic extraction

Abstract A versatile continuous-flow synthesis of highly functionalized 1,2,4-oxadiazoles starting from carboxylic acids is reported. This process was applied to the multistep synthesis of imidazo[1,2-a]pyridin-2-yl-1,2,4-oxadiazoles, using a three reactor, multistep continuous-flow system without isolation of intermediates. This continuous-flow method was successfully combined with a single-step liquid-liquid microextraction unit to remove high boiling point polar solvents and impurities and provides the target compounds in high purity with excellent overall yields. 23

2‑Aminopyridines via Reaction of Pyridine <i>N</i>‑Oxides and Activated Isocyanides

A practical and efficient method for the synthesis of substituted 2-aminopyridines from pyridine <i>N</i>-oxides is reported. Yields of purified, isolated products of up to 84% are observed for the one-pot, two-step process. The reaction involves an in situ deprotection of an isolable <i>N</i>-formylaminopyridine intermediate and facilitates the synthesis of 2-aminopyridines for which other methods fail

Amphiphilic suramin dissolves Matrigel, causing an \u27inhibition\u27 artefact within in vitro angiogenesis assays.

The field of study concerning promotion and/or inhibition of angiogenesis has gathered much attention in the scientific community. A great deal of work has been invested towards defining reproducible assays to gauge for promotion or inhibition of angiogenesis in response to drug treatments or growth conditions. Two common components of these assays were noted by our group to have an unexpected and previously unreported interaction. Suramin is a commercially available compound, commonly used as a positive control for in vitro angiogenic inhibition assays. Matrigel is a popular extracellular substrate that supports angiogenic network formation when endothelial cells are cultured on its surface. However, our group demonstrated that suramin alone (without the presence of cells) will actively dissolve Matrigel, causing the extracellular matrix to transition from the gel-like physical state to a more liquid state. This causes cells on the Matrigel to congregate and sink to the bottom of the well. Therefore, previous observations of inhibition of endothelial cell angiogenesis through the incubation with suramin (including previous observations made by our group) are, largely, an artefact caused by suramin and matrix interaction rather than suramin and cells interaction, as previously reported. Our results suggest that the presence of sulphate groups and amphiphilic properties of suramin are likely responsible for the disruption of the matrix layer. We believe that this information is of prime importance to anyone using similar in vitro models, or employing suramin in any therapy or drug development assays