First total synthesis of (±)-melinonine-E and (±)-strychnoxanthine using a radical cyclization process as the core ring-forming step
First total synthesis of (±)-melinonine-E and (±)-strychnoxanthine using a radical cyclization process as the core ring-forming step
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DOI：
10.1021/jo971148c
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发表时间：
1998-02-20
影响因子：
3.6
通讯作者：
Bonjoch, J
中科院分区：
文献类型：
--
作者：
Quirante, J;Escolano, C;Bonjoch, J
本文首次报道了（+/-）-melinonine-E和（+/-）-strychnoxanthine的全合成。合成这两种生物碱的关键共同步骤是使用α-氨基甲酰基二氯甲基自由基作为供体，通过自由基碳环化制备8-氮杂双环[3.3.1]壬烷核（D和E环）。通过Bischler-Napieralski环化封闭C环，然后进行差向异构化过程以获得轴向腈20，并进行适当的还原转化，得到五环醇23。分别通过C环的钯黑脱氢或相应乙酸酯25的SeO 2氧化将该醇转化为（+/-）-melinonine-E（1）或（+/-）-strychnoxanthine（2）。
The first total synthesis of (+/-)-melinonine-E and (+/-)-strychnoxanthine is described. The key common step for the synthesis of both alkaloids is the elaboration of the 8-azabicyclo[3.3.1]nonane nucleus (D and E rings) by a radical carbocyclization, using an alpha-carbamoyldichloromethyl radical as a donor. The closure of the C ring by a Bischler-Napieralski cyclization, followed by an epimerization process to gain the axial nitrile 20, and appropriate reduction transformations afforded pentacyclic alcohol 23. This alcohol was converted into either (+/-)-melinonine-E (1) or (+/-)-strychnoxanthine (2) by means of a palladium black dehydrogenation of the C ring or a SeO2 oxidation of the corresponding acetate 25, respectively.