Synthesis of 7-epineoptilocaulin, mirabilin B, and isoptilocaulin. A unified biosynthetic proposal for the ptilocaulin and batzelladine alkaloids. Synthesis and structure revision of netamines E and G.
Synthesis of 7-epineoptilocaulin, mirabilin B, and isoptilocaulin. A unified biosynthetic proposal for the ptilocaulin and batzelladine alkaloids. Synthesis and structure revision of netamines E and G.
复制标题
7-epineoptilocaulin、mirabilin B 和 isoptilocaculin 的合成。
DOI：
10.1021/jo801956w
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
Snider,BarryB
中科院分区：
文献类型：
--
作者：
Yu,Min;Pochapsky,SusanS;Snider,BarryB
在85 °C下，将胍添加到6-甲基六氢茚酮的MeOH溶液中，得到7-表新茎梗素。用6-丙基六氢茚酮进行类似的反应，得到netamine E。MnO 2氧化7-epineoptilocaulin和netamine E分别得到mirabilin B和netamine G。netamines的侧链是反式的，而不是最初提出的顺式。一个统一的生物合成计划batzelloculin和ptilocaulin家庭的建议。胍与双烯酮的共轭加成，然后烯醇化物与另一个烯酮的分子内迈克尔反应，羟醛缩合反应，脱水和烯胺形成将导致在脱氢小茎泽兰素氧化态的三环中间体。1，4-氢化物加成将导致ptilocaulin或7-epineoptilocaulin，这取决于氢化物加成到哪一面。1，2-氢化物的加入将导致isoptilocaulin。以四氢茚酮和胍为原料合成了关键的三环中间体，用NaBH 4还原得到了富含ptilocaulin和isoptilocaulin的混合物。
Addition of guanidine to a 6-methylhexahydroindenone in MeOH at 85 °C afforded 7-epineoptilocaulin. A similar reaction with a 6-propylhexahydroindenone afforded netamine E. MnO2oxidation of 7-epineoptilocaulin and netamine E afforded mirabilin B and netamine G, respectively. The netamines have the side chains trans, not cis as was initially proposed. A unified biosynthetic scheme for the batzelladines and ptilocaulin family is proposed. Conjugate addition of guanidine to a bis enone followed by an intramolecular Michael reaction of the enolate to the other enone, aldol reaction, dehydration, and enamine formation will lead to a tricyclic intermediate at the dehydroptilocaulin oxidation state. 1,4-Hydride addition will lead to ptilocaulin or 7-epineoptilocaulin depending on which face the hydride adds to. 1,2-Hydride addition will lead to isoptilocaulin. The key tricyclic intermediate was prepared from a tetrahydroindenone and guanidine and reduced with NaBH4to give a mixture rich in ptilocaulin and isoptilocaulin.