Bromination of phenols in bromoperoxidase-catalyzed oxidations
Bromination of phenols in bromoperoxidase-catalyzed oxidations
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DOI：
10.1016/j.tet.2012.08.081
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发表时间：
2012-11-18
期刊：
影响因子：
2.1
通讯作者：
Hartung, Jens
中科院分区：
文献类型：
--
作者：
Wischang, Diana;Hartung, Jens
苯酚和邻位取代的衍生物提供产品的选择性对位溴化，如果处理与溴化钠，过氧化氢，钒酸盐（V）依赖性溴过氧化物酶I从棕色Ascophyllum nodosum。当苯酚中的邻位取代基从F经Cl、OCH 3、C（CH 3）（3）和H变为CH 3时，在吗啉-4-乙磺酸（MES）缓冲的叔丁醇水溶液（pH 6.2）中溴化的相对速率增加32倍。根据Hammett相关性（rho=-3），通过酶法进行的苯酚溴化中的极性效应与相同条件下分子溴的反应性（rho=-2）进行比较。在叔丁醇水溶液中，次溴酸在pH 6.2时不能亲电地用溴取代氢。三溴阴离子在MES缓冲的叔丁醇水溶液中表现为亲电试剂（rho类似于-3），在苯酚溴化中表现出与分子溴类似的极性效应。(C)2012爱思唯尔有限公司保留所有权利。
Phenol and ortho-substituted derivatives furnish products of selective para-bromination, if treated with sodium bromide, hydrogen peroxide, and the vanadate(V)-dependent bromoperoxidase I from the brown alga Ascophyllum nodosum. Relative rates of bromination in morpholine-4-ethane sulfonic acid (MES)-buffered aqueous tert-butanol (pH 6.2) increase by a factor 32, as the ortho-substituent in a phenol changes from F via Cl, OCH3, C(CH3)(3), and H to CH3. The polar effect in phenol bromination by the enzymatic method, according to a Hammett-correlation (rho=-3), compares to reactivity of molecular bromine under identical conditions (rho=-2). Hypobromous acid is not able to electrophilically substitute bromine for hydrogen at pH 6.2 in aqueous tert-butanol. The tribromide anion behaves in MES-buffered aqueous tert-butanol as electrophile (rho similar to-3), showing a similar polar effect in phenol bromination as molecular bromine. (C) 2012 Elsevier Ltd. All rights reserved.