[摘要]：A formal total synthesis of the spiroketal containing cytotoxic myxobacteria metabolite spirangien A (1) is described. The approach utilizes a late introduction of the C20 alcohol that mirrors the biosynthesis of this compound. The key steps involved a high yielding cross metathesis reaction between enone 6 and alkene 7 to give E-enone 4 and a Mn-catalyzed conjugate reduction alpha-oxidation reaction to introduce the C20 hydroxyl group. Acid treatment of the alpha-hydroxyketone 4 gave spiroketa119 which was converted into known spirangien A (1) advanced intermediate spiroketal 3. |
