is a traditional Chinese tonic herb. Its main medicinal components are secondary metabolites such as flavonoids and flavonol glycosides, but the biosynthetic mechanism is still unclear. Moisture conditions are a key environmental factor affecting medicinal components during harvesting.
View Article and Find Full Text PDFThe asymmetric total synthesis of vinorine, a polycyclic and cage-like alkaloid, has been realized in a flexible approach. Key features of the current synthesis include an aza-Achmatowicz rearrangement/Mannich-type cyclization to install the highly functional 9-azabicyclo-[3.3.
View Article and Find Full Text PDFKopsia alkaloids represent a complex class of natural products bearing a polycyclic ring system with two or three consecutive quaternary carbon centers. In this article, we report the first total synthesis of Kopsaporine related alkaloids. Features of our structure-unit-based strategy are an intramolecular Pummerer rearrangement induced nucleophilic cyclization/aza-Prins cyclization to construct the highly functional hexahydrocarbazole skeleton, an olefin migration vinylogous alkylation to establish the C20 all-carbon quaternary center, an iridium complex mediated radical addition to fuse the aspidofractine framework, an unprecedented IBX oxidation to introduce the α-hydroxyketone moiety, and a bioinspired retro-Aldol/Aldol reaction to convert kopsaporine to kopsiloscine A.
View Article and Find Full Text PDFImidazoles are among the most important pharmacophores in medicinal chemistry. Herein we report a tandem protocol for the synthesis of highly substituted imidazoles through Pummerer-like rearrangement induced cascade reactions including two carbon-nitrogen bond formations, and concomitant aromatization under mild reaction conditions. This procedure gives imidazole derivatives bearing numerous functional groups and could be used for modifying natural products as well as pharmaceuticals.
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