The plakotenins: biomimetic Diels-Alder reactions, total synthesis, structural investigations, and chemical biology.

The total synthesis of plakotenin, a cytotoxic marine natural product, using a biomimetic Diels-Alder reaction is described in detail. Two approaches were used, whereby the Diels-Alder reaction occurs at different stages of the synthesis. Homo- and nor-plakotenin, related natural products, were also prepared, as well as iso-plakotenin, a diastereoisomer of plakotenin.

Structure revision of plakotenin based on computational investigation of transition states and spectroscopic properties.

We show that the previously [Tetrahedron Lett.1992, 33, 2579] proposed structure of natural plakotenin must be revised. Recently, the total synthesis of plakotenin was achieved via an intramolecular Diels-Alder reaction from a (E,E,Z,E)-tetraene as linear precursor.

A unified strategy for the asymmetric total syntheses of diversonol and lachnone C.

A unified synthetic strategy for the asymmetric syntheses of the natural products diversonol and lachnone C was developed by using the domino vinylogous aldol-oxa-Michael reaction as the enantioselective key step. Further transformations include dihydroxylation, lactol-opening by a Wittig-reaction, and lactonization. The obtained chromone lactones, a class of mycotoxins, can further be converted to tetrahydroxanthones by a Dieckmann condensation.

Synthetic studies towards marmycins A and B: development of the vinylogous aldol-aza-Michael domino reaction.

The vinylogous aldol-aza-Michael domino reaction between 2-aminobenzaldehydes and prenal was developed to build up the core of natural products marmycin A and B without the need of protective groups.

Enantioselective total synthesis of plakotenin, a cytotoxic metabolite from Plakortis sp.

The first total enantioselective synthesis of plakotenin is described. This marine natural product was isolated from an Okinawan sponge of the genus Plakortis and shows potent biological activity against several cancerous cell lines. A biomimetic intramolecular Diels-Alder reaction served as a key step in the total synthesis.