The jatrophane diterpene Pl-3, isolated in 2003 from Euphorbia platyphyllos, is a structurally complex natural product with highly promising biological properties that include pronounced antiproliferative activity and the inhibition of the efflux-pump activity of multidrug resistance p-glycoprotein. Herein, the synthesis of the eastern fragment of Pl-3 is outlined. The target compound is synthesized in nine synthetic operations in good overall yield, starting from readily available d-ribose. The key step in the preparation of the eastern part of Pl-3 is a diastereoselective SmI2-mediated Reformatsky reaction. The proposed route is highly flexible and could also be applied to the synthesis of structurally related jatrophane diterpenes.
Jatrophane diterpenes are structurally intriguing natural products with promising biological properties. Herein, the synthesis of the western fragment of the Euphorbiaceae constituent Pl‐3 starting from (1R,5S)‐bicyclo[3.2.0]hept‐2‐en‐6‐one is described. Key steps in the sequence include a Baeyer–Villiger oxidation, an iodolactonization reaction, and the installation of the northern side chain through the addition of a lithiated vinyl bromide. The overall efficiency of the route is increased by taking advantage of latent symmetry.
The
preparation of an advanced intermediate toward the synthesis
of the jatrophane diterpene Pl-4 is described. The key step is a regioselective
chelation-controlled lithiation of the (Z)-configured
bromide in the corresponding vinyl dibromide precursor. The method
outlined within this Article is suitable for the facile access of
sterically hindered internal vinyl halides for further coupling reactions.
Jatrophane diterpenes, isolated from members of the Euphorbiaceae plant family, constitute a class of biologically and structurally intriguing natural products. Herein, different strategies for the preparation of an advanced intermediate towards the total synthesis of the jatrophane diterpene Pl-4 are described. Key strategies for the elaboration of the jatrophane precursors include hydrometalation and radical reactions.
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