Base-catalyzed C-H deprotonation of 4-methoxybenzyl alcohol radical cations in water: Evidence for a carbon-to-oxygen 1,2-H-shift mechanism
Base-catalyzed C-H deprotonation of 4-methoxybenzyl alcohol radical cations in water: Evidence for a carbon-to-oxygen 1,2-H-shift mechanism
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DOI：
10.1021/ja970259q
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发表时间：
1997-04-30
影响因子：
15
通讯作者：
Steenken, S
中科院分区：
文献类型：
--
作者：
Baciocchi, E;Bietti, M;Steenken, S
自由基阳离子的裂解反应，特别是那些涉及CH和CC键断裂的裂解反应，由于其许多实际和理论意义而引起了人们的持续关注。2在这个研究领域，我们最近报道，在水溶液中，R-OH基团的存在有助于烷基芳基阳离子中CC键的断裂。3观察到碱催化作用，提出了氢键过渡态。为了更好地解释这一现象，我们现在发现，R-OH基团也可以帮助CH键的断裂(CH去质子化)。我们的研究结果使我们能够对自由基阳离子裂解反应中R-OH基团的性质得出更一般的结论。起点是OH-对自由基阳离子1·+和2·+的裂解反应，前者涉及CC键(式1，B代表碱基)的裂解，而后者涉及CH键(式2)的裂解。
Fragmentation reactions of radical cations, and particularly those involving CH and CC bond cleavage, are attracting continuous interest due to their many practical and theoretical implications. 2 In this research area, we recently reported that, in aqueous solution, the cleavage of a CC bond in alkylaromatic radical cations is assisted by the presence of an R-OH group. 3 Base catalysis was observed, and a hydrogen-bonded transition state was suggested. In an effort to throw more light on this phenomenon, we have now discovered that an R-OH group can assist as well the cleavage of a CH bond (CH deprotonation). The results of our study, which permit more general conclusions to be drawn on the nature of the R-OH group assistance in fragmentation reactions of radical cations, are presented herewith.The starting point was the similar effect of OH-on the fragmentation reactions of the radical cations 1•+ and 2•+, the former of which involves the cleavage of the CC bond (eq 1, B symbolizes a base) and the latter one, however, that of the CH bond (eq 2).