OXYGENATION OF TERT-BUTYLPHENOLS WITH AN UNSATURATED SIDE-CHAIN
OXYGENATION OF TERT-BUTYLPHENOLS WITH AN UNSATURATED SIDE-CHAIN
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DOI：
10.1021/jo00362a018
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发表时间：
1986-06-13
影响因子：
3.6
通讯作者：
MATSUURA, T
中科院分区：
文献类型：
--
作者：
NISHINAGA, A;IWASAKI, H;MATSUURA, T
本文研究了碱和Co（Salpr）促进的标题化合物的氧合反应，以期获得有关区域选择性引入O2的控制因素的进一步细节。在4-烯基-2，6-二叔丁基苯酚和2-烯基-4，6-二叔丁基苯酚的氧化中，（1和12），底物的反应性和O2掺入的区域选择性可以根据链烯基的电子和空间效应以及抗衡阳离子K+对过渡态的缔合效应来解释。状态26涉及从底物阴离子到O2的电荷转移。对于4-炔基-2，6-二叔丁基苯酚（21），仅当酚盐阴离子与K+缔合时，分子氧才仅结合到邻位。相反，在1和12与Co（Salpr）的氧化中，O2仅并入烯基侧链中，而不管取代基的性质如何，而对于21，O2并入分布于邻位和炔基侧链两者。酚类化合物与Co（Salpr）氧化反应的取代基依赖性区域选择性是因为反应性酚酸盐-Com物种进行均裂形成苯氧基自由基-Co 11物种，它们的氧化相互竞争。当阴离子物质的氧化占主导地位时，O2被掺入邻位，而对于自由基物质，帕拉和侧链氧化占主导地位。
Base-andCo (Salpr)-promoted oxygenations of title compounds havebeen investigated with a view to obtaining further details concerning controlling factors in regioselective 02 incorporation into phenols. In the oxygenation of 4-alkenyl-2, 6-di-tert-butyl-and 2-alkenyl-4, 6-di-tert-butylphenols (1 and 12), the reactivity of the substrates and regioselectivityin the 02 incorporation may be interpreted in terms of electronic and steric effects of the alkenyl group as well as association effect of the countercation K+ on the transition-state 26 involving a charge transfer from the substrate anion to 02. With 4-alkynyl-2, 6-di-tert-butylphenols (21), dioxygen was incorporated exclusively into the ortho position only when the phenolate anion was associated with K+. On the contrary, in the oxygenation of 1 and 12 with Co (Salpr), 02 was incorporated exclusively into the alkenyl side chain, regardless of the nature of the substituent, whereas with 21, 02 incorporation was distributed to both the ortho and the alkynyl side chain. Thesubstituent-dependent regioselectivity in the oxygenation of phenols with Co (Salpr) is because the reactive phenolate-Com species undergo homolysis to form phenoxy radical-Co11species reversibly, whose oxygenations compete with each other. When the oxygenation of the anionic species predominates, 02 is incorporated into the ortho position, whereas with the radical species the para and side chain oxidations predominate.