Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India.
Chemistry. 2010 Sep 10;16(34):10576-91. doi: 10.1002/chem.201000394.
The synthesis and reactivity of 2,6-disubstituted arylselenium compounds derived from 2-bromo-5-tert-butylisophthalic acid (43) are described. The syntheses of bis(5-tert-butylisophthalic acid dimethyl ester)diselenide (46) and bis(5-tert-butylisophthalic acid diisopropyl ester)diselenide (47) have been achieved by the reaction of the corresponding ester precursors with disodium diselenide. Reduction of diselenide 46 with lithium aluminum hydride affords 2,2'-bis(5-tert-butylbenzene-1,3-dimethanol)diselenide (53). Diselenides 46 and 47 exhibit intramolecular Se...O interaction. Compound 53 does not show any intramolecular Se...O interaction. The anomalous Se...O nonbonded coordination observed in the single-crystal X-ray structures of compounds 46, 47 and 53 is compared and contrasted. The corresponding selenenyl bromides 54 and 55, derived from the reaction of diselenides 46 and 47 with bromine, are quite stable in the solid state. However, they undergo hydrolysis and subsequent intramolecular cyclization upon heating or after having been kept in solution over a period of time to give the corresponding selenenate esters 56 and 57. The X-ray crystallographic study and density functional theory calculations on 54 at the B3LYP/6-31G(d) level of theory indicate a significant distortion in planarity of the aromatic ring. Glutathione peroxidase-like activities of diselenides 46 and 47 and their selenenate esters 56 and 57 have been studied both by thiophenol and bioassay methods. The very low glutathione peroxidase-like activity of the diselenides (46 and 47) and their selenenate esters (56 and 57) in the thiophenol assay is attributed to the presence of the relatively strong Se...O intramolecular interaction in the selenenyl sulfide intermediates. The interaction retards the catalytic activity through both thiol exchange and an intramolecular cyclization reaction.
本文描述了由 2-溴-5-叔丁基间苯二甲酸（43）衍生的 2,6-二取代芳硒化合物的合成和反应性。通过相应酯前体与二硒化二钠的反应，已经合成了双（5-叔丁基间苯二甲酸二甲酯）二硒化物（46）和双（5-叔丁基间苯二甲酸二异丙酯）二硒化物（47）。用氢化锂铝还原二硒化物 46 得到 2,2'-双（5-叔丁基苯-1,3-二甲醇）二硒化物（53）。二硒化物 46 和 47 表现出分子内 Se...O 相互作用。化合物 53 没有表现出任何分子内 Se...O 相互作用。在化合物 46、47 和 53 的单晶 X 射线结构中观察到的异常 Se...O 非键配位进行了比较和对比。由二硒化物 46 和 47 与溴反应得到的相应硒溴化物 54 和 55 在固态下非常稳定。然而，它们在加热或在溶液中保存一段时间后会发生水解和随后的分子内环化，得到相应的硒酸盐酯 56 和 57。在 B3LYP/6-31G(d)理论水平上对 54 进行的 X 射线晶体学研究和密度泛函理论计算表明，芳环的平面性发生了显著扭曲。通过噻酚和生物测定方法研究了二硒化物 46 和 47 及其硒酸盐酯 56 和 57 的谷胱甘肽过氧化物酶样活性。在噻酚测定中，二硒化物（46 和 47）及其硒酸盐酯（56 和 57）的谷胱甘肽过氧化物酶样活性非常低，这归因于在硒代硫醚中间体中存在相对较强的 Se...O 分子内相互作用。这种相互作用通过巯基交换和分子内环化反应来减缓催化活性。
