Synthesis of clionamine B, an autophagy stimulating aminosteroid isolated from the sponge Cliona celata

Clionamine B (2), an aminosteroid isolated from the marine Sponge Cliona celata, has been synthesized starting from the plant sapogenin tigogenin (5). A key step in the synsthesis is the stereoselective introduction of the C-20 α-hydroxyl substituent via oxidation of a γ-lactone enolate with molecular oxygen. Synthetic clionamine B (2) strongly stimulated Autophagy in human breast Cancer MCF-7 cells.