55 タクスシン合成研究(ポスター発表の部)

概要

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Taxane family has a unique tricyclo [9.3.1.0.^<3,8>] pentadecane skeleton and some of them (taxol 2 and cephalomannnine 3 ) are known to have several important biological activities. Our synthetic approach toward taxusin 4 includes the cationic intramolecular 8-membered ring cyclizaton of dienol silyl ether with acetal. Dienol silyl ether containing an acetal moiety 23 was prepared in 12 steps from enol ether 10 and treatment of 23 with TMSOTf in CH_2Cl_2 gave the desired 8-membered ring product 27. It should be noted that the product 27 obtained here was a single stereoisomer with the correct stereochemistry of natural taxanes. This reaction has provided a powerful method to resolve three of the most difficult problems for taxane synthesis. 1) an efficient cyclizaton of eight-memebered B ring 2) a complete stereocontrol of the C-9 and C-10 functional groups 3) a complete control of endo conformation of A and C ring Further this product 27 is easily converted to taxusin and we are now pursuing a total synthesis of taxusin by applying this methodology.
天然有機化合物討論会の論文
1990-09-25