385809-16-5Relevant academic research and scientific papers
Total synthesis of the microtubule stabilizing antitumor agent laulimalide and some nonnatural analogues: The power of sharpless' asymmetric epoxidation
Ahmed, Anjum,Hoegenauer, E. Kate,Enev, Valentin S.,Hanbauer, Martin,Kaehlig, Hanspeter,Ohler, Elisabeth,Mulzer, Johann
, p. 3026 - 3042 (2007/10/03)
Three different routes are described for the synthesis of deoxylaulimalide (3), which is the immediate precursor of the marine sponge metabolite laulimalide (1). These routes mainly differ with respect to their ring closing step. Thus, route 1 uses a Still-Gennari olefination, route 2 a Yamaguchi lactonization, and route 3 an intramolecular allylsilane-aldehyde addition for establishing the macrocyclic structure. The unprotected deoxy derivative 3 was subjected to Sharpless' asymmetric epoxidation (SAE). With (R,R)-tartrate the 16,17-epoxide laulimalide (1) is formed selectively, whereas (S,S)-tartrate generates the 21,22-epoxide 142. This demonstrates the high reagent control involved in the SAE process, which in this case is used to achieve high stereo- and regioselectivity. Laulimalide and some derivatives thereof have been tested with respect to antitumor activity and compared to standard compounds paclitaxel and epothilone B.
An intramolecular case of sharpless kinetic resolution: Total synthesis of laulimalide
Mulzer, Johann,Oehler, Elisabeth
, p. 3842 - 3846 (2007/10/03)
The microtubule-stabilizing antitumor agent laulimalide (1) has been obtained in by new synthetic route. The carbon skeleton was assembled by means of Julia-Kocienski (C16-C17) and Horner-Wadsworth-Emmons (C21-C22) olefinations. Still-Gennari olefination
Total synthesis of microtubule-stabilizing agent (-)-laulimalide
Ghosh,Wang,Kim
, p. 8973 - 8982 (2007/10/03)
An enantioselective first total synthesis of laulimalide (1) is described. Laulimalide, a remarkably potent antitumor macrolide, has been isolated from the Indonesian sponge Hyattella sp. and the Okinawan sponge Fasciospongia rimosa. Laulimalide represents a new class of antitumor agents with significant clinical potential. The synthesis is convergent and involved the assembly of C3-C16 segment 4 and C17-C28 segment 5 by Julia olefination. The sensitive C2-C3 cis-olefin functionality was installed by Yamaguchi macrolactonization of a hydroxy alkynic acid followed by hydrogenation of the resulting alkynoic lactone over Lindlar's catalyst. Initial attempts of intramolecular Still's variant of Horner - Emmons olefination between the C19-phosphonocetate and C3-aldehyde provided a 1:2 mixture of cis- and trans-macrolactones. The trans-isomer was photo-isomerized to a mixture of cis- and trans-isomers. The other key steps involved ring-closing olefin metathesis to construct both dihydropyran units, stereoselective anomeric alkylation to functionalize the dihydropyran ring, stereoselective reduction of the resulting alkynyl ketone to set the C20-hydroxyl stereochemistry, and a novel Julia olefination protocol for the installation of the C13-exomethylene unit. The sensitive epoxide at C16-C17 was introduced in a highly stereoselective manner by Sharpless epoxidation at the final stage of the synthesis.
