Combined computational and experimental studies of the mechanism and scope of the retro-Nazarov reaction
Combined computational and experimental studies of the mechanism and scope of the retro-Nazarov reaction
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DOI：
10.1021/ja048942h
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发表时间：
2004-09-08
影响因子：
15
通讯作者：
Kirchhoefer, PL
中科院分区：
文献类型：
--
作者：
Harmata, M;Schreiner, PR;Kirchhoefer, PL
密度泛函理论计算（B3 LYP/6-31 +G*）表明，在环戊烯基氧烯丙基阳离子的碳3和碳4上的共轭和供电子取代基对这些物种的逆Nazarov反应具有速率加速作用.当碳三被甲氧基和甲基取代时，这些中间体的逆Nazarov反应预计将表现出显着的torquosectivity。实验研究表明，当两个烷基和一个芳基/乙烯基在碳3和碳4上时，氧烯丙基阳离子可以进行有效的逆Nazarov反应。相同数目的烷基取代基或单个芳基取代基在促进反应方面是无效的。有趣的是，在碳三上的单个烷氧基取代基足以使逆纳扎罗夫反应发生。所开发的方法用于天然产物姜酮的全合成。
Density functional theory calculations (B3LYP/6-31 +G*) demonstrate that conjugating and electron-donating substituents at carbons three and four of a cyclopentenyl oxyallylic cation should have a rate-accelerating effect on the retro-Nazarov reactions of these species. The retro-Nazarov reaction of these intermediates is predicted to exhibit significant torquoselectivity when carbon three is substituted with a methoxy and a methyl group. Experimental studies show that oxyallylic cations can undergo effective retro-Nazarov reactions when two alkyl and one aryl/vinyl groups are on carbons three and four. An equal number of alkyl substituents or a single aryl substituent is not effective in promoting the reaction. Interestingly, a single alkoxy substituent at carbon three is sufficient for the retro-Nazarov reaction to occur. The methodology developed was used in a total synthesis of the natural product turmerone.