A domino approach to the enantioselective total syntheses of blennolide C and gonytolide C.
A domino approach to the enantioselective total syntheses of blennolide C and gonytolide C.
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DOI：
10.1002/chem.201402495
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发表时间：
2014-07
期刊：
影响因子：
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通讯作者：
L. Tietze;Stefan Jackenkroll;Judith Hierold;Ling Ma;Bernd Waldecker
中科院分区：
文献类型：
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作者：
L. Tietze;Stefan Jackenkroll;Judith Hierold;Ling Ma;Bernd Waldecker
首次报道了四氢呫吨酮 (-)-blennolide C (ent-4) 和相关的 γ-内酯基色满酮 (-)-gonytolide C (ent-3) 的对映选择性全合成。合成的关键是通过对映选择性多米诺-瓦克/羰基化/甲氧基化反应在 C-4a 处建立立体中心。研究了各种手性 BOXAX 配体，包括新型 (S,S)-iBu-BOXAX，并允许以 99% 的优异对映选择性获得色烷 8。 C-4 处的第二个立构中心是采用非对映选择性 Sharpless 二羟基化建立的。对基于 (DHQ) 和 (DHQD) 的配体的广泛研究使得能够分别以非常好的至合理的选择性 13.7:1 和 1:3.7 制备反式异构体 14a 和顺式异构体 14b。当 14a 进一步转化为 ent-3 和 ent-4 时，14b 被精制为顺式酸 25 和 2'-epi-gonytolide C 28。
The first enantioselective total syntheses of the tetrahydroxanthenone (-)-blennolide C (ent-4) and related γ-lactonyl chromanone (-)-gonytolide C (ent-3) are reported. Key to the syntheses is an enantioselective domino-Wacker/carbonylation/methoxylation reaction to set up the stereocentre at C-4a. Various chiral BOXAX ligands were investigated, including novel (S,S)-iBu-BOXAX, and allowed access to chromane 8 in an excellent enantioselectivity of 99 %. The second stereocentre at C-4 was established employing a diastereoselective Sharpless dihydroxylation. An extensive survey of (DHQ)- and (DHQD)-based ligands enabled the preparation of both the anti-isomer 14 a and the syn-isomer 14 b in very good to reasonable selectivities of 13.7:1 and 1:3.7, respectively. While 14 a was further converted to ent-3 and ent-4, 14 b was elaborated to syn-acid 25 and 2'-epi-gonytolide C 28.