Biomimetic Syntheses of Amorfrutin C and C ‐5 Substituted Amorfrutin Analogues

Amorfrutin C, a C ‐5 prenyl amorfrutin, its allyl analog and an amorfrutin C ‐5 aldehyde have been synthesized using a biomimetic strategy from non‐aromatic precursors. In this approach, a dioxinone derived β,δ‐ diketo ester underwent a decarboxylative Pd(0) catalyzed prenyl migration to give a β,δ‐ diketo dioxinone, which readily aromatized giving the amorfrutin core. The introduction of prenyl and allyl moieties at the C ‐5 position of the scaffold was accomplished using a Claisen rearrangement. Alternatively, iodination, lithium‐iodine exchange and trapping with DMF gave the amorfrutin aldehyde and an amorfrutin alcohol when excess n ‐BuLi was used.