The Cytoskyrin Cascade: A Facile Entry into Cytoskyrin A, Deoxyrubroskyrin, Rugulin, Skyrin, and Flavoskyrin Model Systems

✍ Scribed by K. C. Nicolaou; Charles D. Papageorgiou; Jared L. Piper; Raj K. Chadha

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 269 KB
• Volume: 44
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.200502011

✦ Synopsis

The collection of naturally occurring compounds shown in Scheme 1 (I: cytoskyrin A, [1] II: deoxyrubroskyrin, [2a] III: rugulin, [3] IV: skyrin, [2b, 4] and V: flavoskyrin [2a] ) represents a growing class of natural products often referred to as bisanthraquinones. Notable among them are cytoskyrin A, [1] the newest member of the class whose striking biological activity includes potency down to 12.5 ng mL À1 in the biochemical induction assay (BIA), and rugulin, whose structural motif exhibits the highest strain of them all. Isolated from small-scale cultures of the endophytic fungus CR200 (Cytospora sp.), which were collected from a branch of a Conocarpus erecta tree in the Guanacaste Conservation area of Costa Rica, cytoskyrin A (I) presents a challenging synthetic target by virtue of its cagelike structural motif, as do its siblings whose more (III) or less (II and V) enclosed cages are defined by the number of bonds linking their two