Nitrobenzoxadiazole derivatives of the rat selective toxicant norbormide as fluorescent probes for live cell imaging.

Norbormide [5-(α-hydroxy-α-2-pyridylbenzyl)-7-(α-2-pyridylbenzylidene)-5-norbornene-2,3-dicarboximide] (NRB, 1), an existing but infrequently used rodenticide, is known to be uniquely toxic to rats, but relatively harmless to other rodents and mammals. As a vasoactive agent, NRB induces a species-specific vasocontractile effect that is restricted to the peripheral arteries of the rat. Despite the precise mechanisms behind this phenomenon having yet to be fully clarified, it is postulated that the molecular target of NRB could be located within the plasma membrane of rat peripheral artery myocytes (e.

Gold catalysis: synthesis of spiro, bridged, and fused ketal natural products.

In the last decade the use of homogenous gold catalysts has rapidly grown and become a valuable tool for complex natural product synthesis. Spiroketal natural products are valuable targets for total synthesis and medicinal chemistry applications. The use of gold catalysts has emerged as a useful tool to synthesise these privileged scaffolds.

Total Synthesis of the Resorcyclic Acid Lactone Spiroketal Citreoviranol.

The first total synthesis of resorcyclic acid lactone spiroketal citreoviranol (1) is described. The synthesis was completed in nine steps and via Sonogashira cross-coupling, gold-catalyzed cyclization, and an unusual base-induced ketalization. The relative and absolute stereochemistry of citreoviranol was unambiguously confirmed using 2D NMR spectroscopy and X-ray crystallography.

Recent developments in transition metal-catalysed spiroketalisation.

The spiroketal motif occurs in a wide range of biologically active natural products and represents a valuable target in medicinal chemistry and total synthesis. In recent years, innovative new synthetic methods have substantially expanded the range of potential precursors, cyclisation modes and opportunities for asymmetric catalysis and tandem processes. This Perspective aims to highlight recent rapid advances in the use of transition metal catalysis for spiroketal formation, in the context of our own investigations into gold-catalysed asymmetric spiroketalisation.