Total Syntheses of ent-Heliespirones A and C
Total Syntheses of ent-Heliespirones A and C
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DOI：
10.1021/jo201971g
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发表时间：
2012-01-06
影响因子：
3.6
通讯作者：
Pettus, Thomas R. R.
中科院分区：
文献类型：
--
作者：
Bai, Wen-Ju;Green, Jason C.;Pettus, Thomas R. R.
对映螺旋酮A和C的立体分散全合成均在11个容器中完成，合并总收率（A + C）为24%。这些合成采用了在延伸共轭的γ-δ不饱和邻醌甲基化物的替代物和L-乳酸衍生的环外烯醇醚之间的相同的逆需求Die Is桤木反应。特别值得注意的新反应包括通过三氟化硼醚合物和三乙基硅烷的组合的色满螺缩酮的非对映选择性还原，沿着通过氧化银（Ago）将色满醚环氧化断裂成相应的对苯醌。此外，观察到硝酸铈铵引起的3度醇的不寻常的分子内醚化。
Stereodivergent total syntheses of ent-heliespirone A and C were both completed in 11 vessels and similar to 24% combined overall yield (A + C). These syntheses employed an identical inverse demand Die Is Alder reaction between a surrogate for an extendedly conjugated gamma-delta unsaturated orthoquinone methide and L-lactic-acid-derived exocyclic enol ether. Novel reactions of special note include a diastereoselective reduction of a chroman spiroketal by combination of borontrifluoride etherate and triethyl silane, along with oxidative rupture of a chroman etherial ring into the corresponding p-quinone by argentic oxide (Ago). In addition, an unusual intramolecular etherification of a 3 degrees alcohol caused by cerium ammonium nitrate was observed.