Bromine as the ortho-directing group in the aromatic metalation/silylation of substituted bromobenzenes
Bromine as the ortho-directing group in the aromatic metalation/silylation of substituted bromobenzenes
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DOI：
10.1021/jo034790h
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发表时间：
2003-11-28
影响因子：
3.6
通讯作者：
Serwatowski, J
中科院分区：
文献类型：
--
作者：
Lulinski, S;Serwatowski, J
研究了带有吸电子取代基p-，m-，o-XC_6 H_4 Br（X = F，Cl，I，CN，CF_3）的溴苯在2当量二异丙基氨基锂（LDA）和2当量三甲基氯硅烷（TMSCl）存在下的一锅法金属化/二甲硅烷基化反应。对位取代溴苯的二甲硅烷基化反应效果最好，但取代基的邻位导向能力对反应的区域选择性有很大影响。相反，间位取代的溴苯的二甲硅烷基化在某些情况下不是有效的或甚至失败，因此单甲硅烷基化的衍生物被分离为主要或唯一的产物。对于邻位取代的溴苯，例如，2-溴苄腈和2-溴氯苯分别以高产率和中等产率转化为相应的二甲硅烷基化衍生物，而1-溴-2-（三氟甲基）苯仅进行单甲硅烷基化。
The one-pot metalation/disilylation of selected bromobenzenes bearing electron-withdrawing substituents p-, m-, o-XC6H4Br (X = F, Cl, I, CN, CF3) using 2 equiv of lithium diisopropylamide (LDA) and 2 equiv of chlorotrimethylsilane (TMSCl) was investigated. The best results of disilylation were obtained for para-substituted bromobenzenes, but the regioselectivity of the reaction is strongly influenced by the ortho-directing power of the substituent. On the contrary, the disilylation of meta-substituted bromobenzenes was not efficient or even failed in some cases and hence monosilylated derivatives were isolated as major or sole products. Diverse reactivity was observed for ortho-substituted bromobenzenes, e.g., 2-bromobenzonitrile and 2-bromochlorobenzene, were converted into corresponding disilylated derivatives in a high and moderate yield, respectively, whereas 1-bromo-2-(trifluoromethyl)benzene underwent only monosilylation.