Stereoselective Total Synthesis of Rhodocoranes I and J

We report the stereoselective total synthesis of rhodocoranes I and J in 10 steps and 16.4% overall yield from (<i>S</i>)-limonene. The synthesis was accomplished through the convergent assembly of a highly substituted chiral cyclopentanone and a lithiated furanyl silyl ketene acetal. The requisite cyclopentanone framework was strategically constructed from the chiral pool, (<i>S</i>)-limonene, through a sequence of steps that included a hydroboration/oxidation, ozonolysis, aldol condensation, reduction, and palladium-catalyzed diastereoselective allylic transposition. This study provides a general approach to the synthesis of the rhodocorane family, known for their antibacterial, antifungal, and cytotoxic properties.