P-34 リコペルジノシドA及びBの合成研究(ポスター発表の部)

概要

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Lycoperdinoside A(1) and B(2) are novel six-membered lactone glycosides, isolated from the slime mold. Enteridium lycoperdon. Agrycone of 1 and 2 has continuous trisubstituted alkens and seven stereogeni.c centers. We have synthesized synthetic segments 5 and 7 for 1 and 2 enantio- and stereoselectively using palladium-catalyzed hydrogenolysis of alkenyloxiranes with formic acid as key reactions. Starting with the aldehyde 8, Wittig reaction, followed by reduction with DIBAH to the corresponding allylic alcohol 9 and Sharpless asymmetric epoxidation gave the optically active (E)-alkenyloxirane 10. The reductive opening reaction of the oxirane 10 with HCO_2H-Et_3N in the presence of palladium catalyst was carried out with retension of stereochemistry to give the alcohol 11 with high stereoselectivity. After protection of 11 as TBS ether, the alcohol 15 was prepared by similar procedures as 11 and was converted to the Segment B (7) by the hydrogenation and the subsequent acid promoted lactonization. By similar procedures the aldehyde 17 was converted to the lactone 21, followed by α-phenylselenation and the subsequent oxidation with hydrogen peroxide to give the Segment A_1 (5). The ketone 26 was synthesized from 22 by indium promoted allylation followed by Wacker oxidation. Total synthesis of 1 and 2 using the synthetic segments 3 and 4 is under way.
天然有機化合物討論会の論文
2007-08-24