Divergent and Stereoselective Synthesis of Ustusal A, (−)-Albrassitriol, and Elegansin D

Abstract

The first synthesis of ustusal A as well as expeditious access to (−)-albrassitriol is described as featuring a singlet oxygen [4 + 2] cycloaddition, achieving the desired stereoselectivity for the 1,4-cis-hydroxyl groups. Transformation of (+)-sclareolide to III followed by a key Horner–Wadsworth–Emmons (HWE) reaction and stereospecific allylic oxidation facilitated the first synthesis of elegansin D. The biological evaluation of these natural products together with seven elegansin D analogues was performed, among which several elegansin D analogues exhibited potential anticancer activity against liver cancer HepG2 cells (IC50 = 11.99–25.58 μM) with low cytotoxicity on normal liver HL7702 cells (IC50 > 100 μM).

Stereoselective Synthesis of Xylodonin A and 22-Hydroxyxylodonin A and Discovery of Analogues with Cytotoxic Activity

“…Drimane-type sesquiterpenoids have attracted considerable attention in the organic synthesis community. − Efforts to synthesize these compounds have led not only to the development of synthetic strategies but also to the investigation of their potent bioactivities. − Total syntheses of 1 and 2 have not yet been achieved, but should provide sufficient quantities of the natural products to investigate their biological properties. In connection with our interest in the synthesis of bioactive natural products, − herein we report the first synthetic strategy to generate 1 and 2 and representative analogues from the readily available (+)-sclareolide. Compounds synthesized in this study exhibited toxic effects on liver cancer HepG2 cells and low toxicity to normal liver HL7702 cells.…”