Total Syntheses of Cyanthiwigins B,F, and G

A concise and versatile approach toward the preparation of the cyanthiwigin family of cyathane natural products is described. By leveraging a unique double asymmetric catalytic alkylation procedure it is possible to quickly establish two of the most critical stereocenters of the cyanthiwigin framework with high levels of selectivity and expediency. The synthetic route additionally employs both a tandem ring‐closing cross‐metathesis reaction, and an aldehyde‐olefin radical cyclization process, in order to rapidly arrive at the tricyclic cyathane core of the cyanthiwigin molecules. From this unifying intermediate, the preparations of cyanthiwigins B, F, and G are attained swiftly and without the need for protecting groups.     

Stellarins F and G, two new cyclopeptides from Stellaria yunnanensis

In the previous papers,we reported the structural elucidation of stellarins A-E,fivenew cyclopeptides from the fresh roots of Stellaria yunnanensis Franch.Further chemical study on this plant led to the isolation of two other new cyclopeptides named stellarins F(l) and G(2).By a combination of 2D-NMR,enzymatic degradation and FABMS,their structures were established to be cyclo(Gly-Ala-Gly-Ser-Pro-Trp-Phe-Pro) and cyclo(Gly-Ala-Tyr-Leu-Ala),respectively.