Electrochemical synthesis of dimerizing and nondimerizing orthoquinone monoketals
Electrochemical synthesis of dimerizing and nondimerizing orthoquinone monoketals
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DOI：
10.1021/jo048677i
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发表时间：
2004-12-10
影响因子：
3.6
通讯作者：
Quideau, S
中科院分区：
文献类型：
--
作者：
Deffieux, D;Fabre, I;Quideau, S
适当取代的2-甲氧基苯酚或α -（2-甲氧基苯氧基）-2-甲基丙酸在甲醇存在下的阳极氧化可得到稳定的正醌单酮，因此构成了一种有价值的替代使用通常基于有毒金属的化学氧化剂的方法。丙酸衍生物最初转化为o -旋内酯醌双酮，然后选择性水解成所需的单酮化合物。在没有阻断取代基的情况下，正醌单酮自发地经历Diels-Alder二聚化成三环十二烯二烯酮，具有非凡的位点选择性、区域选择性和立体选择性。根据这些正醌单酮衍生环二聚体的分子内[2 + 2]反应性，提出了为这些控制开辟一条期待已久的新轨道的建议。
Anodic oxidation of appropriately substituted 2-methoxyphenols or alpha-(2-methoxyphenoxy)-2-methylpropionic acids in the presence of methanol furnishes stable orthoquinone monoketals, and thus constitutes a valuable alternative to the use of chemical oxidants that are often based on toxic metallic species. The propionic acid derivatives are initially converted into O-spirolactonic quinone bisketals that are then selectively hydrolyzed into the desired monoketal compounds. In the absence of blocking substituents, orthoquinone monoketals spontaneously undergo Diels-Alder dimerizations into tricyclododecadienedienones with extraordinary site selectivity, regioselectivity, and stereoselectivity. Suggestions are made to open up a new track for a long awaited rationalization of these controls on the basis of the intramolecular [2 + 2] reactivity of these orthoquinone monoketal-derived cyclodimers.