Cryptolaevilactones A–F (1–6), isolated from Cryptocarya laevigata by our group, are the first monoterpene–polyketides with a unique spiro[3.5]nonane. Cryptolaevilactones A–C (1–3) and D–F (4–6) are diastereomers and bicyclic lactones 4–6 were also artificially transformed by the treatment of the related monocyclic lactones 1–3 with SiO2 or DBU. The absolute configurations at C-6 and C-8, as well as the relative configurations for other stereocenters, were revealed by the various NMR techniques, CD spectra, and modified Mosher method. However, the determination of total absolute configurations and the evaluation of their biological activity have not been completed because of the limited amount of isolated products. To elucidate all above, the asymmetric total synthesis was attempted through the coupling of the spiro ring moiety with the lactone moiety and cinnamoyl moiety. The synthesis of the spiro ring moiety was achieved by the rearrangement of cyclopropyl phenyl sulfide on chiral cryptone. Keck and Brown asymmetric allylations were applied to construct the stereocenters for the lactone moiety. We will present the synthetic detail and the absolute configurations of isolated natural cryptolaevilactones A–F (1–6).

Total synthesis of unique monoterpene-polyketides, cryptolaevilactones, from Cryptocarya laevigata

2019 Fall National Meeting

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