Total Synthesis of the Diterpene Waihoensene.

A racemic and scalable enantioselective total synthesis of (+)-waihoensene was accomplished. (+)-Waihoensene belongs to the diterpene natural product family, and it features an angular triquinane substructure motif. Its tetracyclic [6.5.5.5]backbone is all-cis-fused, containing six contiguous stereocenters, four of which are quaternary. These structural features were efficiently installed by means of a diastereoselective radical cyclization, followed by an intramolecular Pauson-Khand reaction, a diastereoselective α-alkylation, and a diastereoselective 1,4-addition reaction. Enantioselectivity was introduced at an early stage, by an asymmetric palladium catalyzed decarboxylative allylation reaction on gram scale.

Light-switchable anchors on magnetized biomorphic microcarriers.

Microcarriers with the ability to release and catch substances are highly desired metamaterials and difficult to obtain. Herein, we report a straightforward strategy to synthesize these materials by combining silica-biomorphs with mesocrystals. An easy access to microcarrier hulls with covalently bound spiropyrans as light-switchable anchor points is presented.