Simple, but Challenging: Recent Developments in the Asymmetric Synthesis of Spiroketals

摘要

I he spiroketal moiety, a structural motif frequently found in natural products, significantly contributes to the biological properties of these molecules. Compounds containing this feature range from simple chiral compounds to complex spiroketal polyketides such as reveromycin B (1). Natural products with benzannulated spiroketals (here: aromatic spiroketals) are less common, but prominent and interesting examples, such as berkelic acid (2) and γ-rubromycin (3), are known (Scheme 1). Two recent reviews' provide insight into successfully completed total syntheses of natural products that contain aromatic [5,5]-, [5,6]-, and [6,6]-spiroketal units as key structures.