Superacid-catalyzed reactions of cinnamic acids and the role of superelectrophiles.
Superacid-catalyzed reactions of cinnamic acids and the role of superelectrophiles.
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DOI：
10.1021/jo030327t
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发表时间：
2004-03
期刊：
影响因子：
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通讯作者：
R. Rendy;Yun Zhang;A. McElrea;Alma Gomez;D. Klumpp
中科院分区：
文献类型：
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作者：
R. Rendy;Yun Zhang;A. McElrea;Alma Gomez;D. Klumpp
研究了肉桂酸及其有关化合物的化学。在超强酸催化的芳烃反应中，提出了两种竞争的反应机理。这两种机制都涉及形成双阳离子中间体（超亲电体），并且反应可以导致查尔酮型产物或茚满酮产物。本文报道了用低温（13）C NMR直接观察到的一种双阳离子。我们提供了明确的证据表明，质子化的羧酸基团（或相应的酰基阳离子）可以提高相邻的亲电中心的反应性。三氟甲磺酸也被发现是一种有效的酸催化剂，用于从肉桂酸直接合成一些缺电子查尔酮和杂环查尔酮。
The chemistry of cinnamic acids and related compounds has been studied. In superacid-catalyzed reactions with arenes, two competing reaction mechanisms are proposed. Both mechanisms involve the formation of dicationic intermediates (superelectrophiles), and the reactions can lead to either chalcone-type products or indanone products. The direct observation of a dicationic species (by low-temperature (13)C NMR) is reported. We provide clear evidence that protonated carboxylic acid groups (or the corresponding acyl cation) can enhance the reactivity of an adjacent electrophilic center. Triflic acid is also found to be an effective acid catalyst for the direct synthesis of some electron-deficient chalcones and heterocyclic chalcones from cinnnamic acids.