5,5',6,6'-tetrahydroxy-2,7'-biindolyl | 133991-51-2

• 分子结构分类: 有机化合物 - 有机杂环化合物 - 吲哚及其衍生物
• 英文名称: 5,5',6,6'-tetrahydroxy-2,7'-biindolyl
• 英文别名: 2-(5,6-dihydroxy-1H-indol-7-yl)-1H-indole-5,6-diol；7-(5,6-dihydroxy-1H-indol-2-yl)-1H-indole-5,6-diol
• CAS: 133991-51-2
• 化学式: C₁₆H₁₂N₂O₄
• 分子量: 296.282
• InChiKey: ZRACRUXIUBFFQC-UHFFFAOYSA-N

物化性质

• 沸点：
  741.1±60.0 °C(Predicted)
• 密度：
  1.709±0.06 g/cm3(Predicted)

计算性质

• 辛醇/水分配系数(LogP)：
  2.4
• 重原子数：
  22
• 可旋转键数：
  1
• 环数：
  4.0
• sp3杂化的碳原子比例：
  0.0
• 拓扑面积：
  113
• 氢给体数：
  6
• 氢受体数：
  4

反应信息

• 作为反应物：
  描述：

  5,5',6,6'-tetrahydroxy-2,7'-biindolyl 在 双氧水 、 potassium carbonate 作用下， 生成 1H-吡咯-2,3-二甲酸 、 2,3,5-三羧酸吡咯
  参考文献：
  名称：

  Oxidative degradation of melanins to pyrrole acids: A model study

  摘要：

  The origin of pyrrole-2,3,5-tricarboxylic acid (PTCA), the most characteristic degradation product of melanins, was investigated by use of synthetic pigments prepared from the major biosynthetic precursors, 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA). Under the reported conditions, i.e. acidic permanganate, oxidative degradation of DHI- and DHICA-melanins afforded PTCA in 0.15 and 3.0% w/w yield, respectively. A significant improvement of PTCA yields up to 7% was obtained using alkaline hydrogen peroxide as the oxidising agent. Under these conditions pyrrole-2,3-dicarboxylic acid (PDCA) was also obtained in significant yields. Investigation of the oxidative degradation of some model indole oligomers (1-4) provided unambiguous evidence that PTCA may originate from 2-linked DHI-units in the pigment polymer as well as from DHICA-derived units, whereas PDCA arises from DHI-units not substituted at 2-position. Monitoring of the oxidation of dimer 1 to PTCA showed the intermediate formation of DHICA. Accordingly, a mechanistic route is proposed for the degradation of 2-substituted DHI-units in melanin polymer to PTCA which also accounts for the observed yields of formation of the pyrrole acid from the model oligomers.

  DOI：

  10.1016/0040-4020(95)00259-b
• 作为产物：
  描述：

  5,5',6,6'-tetraacetoxy-2,7'-biindolyl 在 sodium phosphate 、 potassium bromide 作用下， 以 甲醇 为溶剂， 反应 0.02h， 生成 5,5',6,6'-tetrahydroxy-2,7'-biindolyl
  参考文献：
  名称：

  从 5,6-二羟基吲哚二聚体到真黑素聚合物的短寿命醌类物质：综合化学、脉冲辐射分解和量子力学研究

  摘要：

  已经研究了由 5,6-二羟基吲哚 (1) 的三个二聚体氧化形成的瞬态物种，这是天然生物聚合物真黑色素的主要组成部分。5,5',6,6'-四羟基-2,4'-二吲哚基 (3) 和 5,5',6,6'-四羟基-2,7'-二吲哚基 (4) 的脉冲辐解氧化导致半醌吸收大约 450 nm，它以二级动力学（分别为 2k=2.8x10(9) 和 1.4x10(9) M-1 s-1）衰减，得到相应的醌（500-550 nm）。另一方面，5,5',6, 6'-四羟基-2,2'-二吲哚基 (2) 提供了一种半醌 (lamdamax=480 nm)，其歧化速率相当 (2k=3x10(9) M -1 s-1) 得到相对稳定的醌 (lamdamax=570 nm)。邻醌、醌亚胺的量子力学研究 2-4 的醌甲基化物结构表明氧化的 2-4 主要以 2-取代的扩展醌甲基化物互变异构体形式存在。最后，首次分离出 3 的氧化产物，并将其配制成羟基化衍生物

  DOI：

  10.1021/ja0650246

文献信息

• Efficient Synthesis of 5,6-Dihydroxyindole Dimers, Key Eumelanin Building Blocks, by a Unified <i>o</i>-Ethynylaniline-Based Strategy for the Construction of 2-Linked Biindolyl Scaffolds
  作者：Luigia Capelli、Paola Manini、Alessandro Pezzella、Alessandra Napolitano、Marco d’Ischia

  DOI：10.1021/jo901259s

  日期：2009.9.18

  A unified convenient strategy for the synthesis of 5,6-dihydroxyindole-derived 2,7′-, 2,2′-, and 2,3′-biindolyls is reported, which is based on proper manipulation of key o-ethynylaniline precursors. By the same methodology 5,6-diacetoxy-7-iodoindole can also be obtained in good yield.

  报道了一种基于5,6-二羟基吲哚衍生的2,7'-，2,2'-和2,3'-二吲哚合成方便的统一策略，该策略基于对关键的邻乙炔基苯胺前体的正确处理。通过相同的方法，也可以良好的产率获得5，6-二乙酰氧基-7-碘吲哚。
• 5,6-Dihydroxyindole Oxidation in Phosphate Buffer/Polyvinyl Alcohol: A New Model System for Studies of Visible Chromophore Development in Synthetic Eumelanin Polymers
  作者：Alessandro Pezzella、Veronica Ambrogi、Marianna Arzillo、Alessandra Napolitano、Cosimo Carfagna、Marco D’Ischia

  DOI：10.1111/j.1751-1097.2010.00730.x

  日期：——

  AbstractThe determinants of the broadband absorption spectrum of eumelanins are still largely unknown. Herein we report a novel approach to investigate eumelanin chromophore which is based on the biomimetic oxidation of the key monomer precursor, 5,6‐dihydroxyindole (DHI, 1), with peroxidase/hydrogen peroxide in phosphate buffer, pH 7, containing 1–5% polyvinylalcohol (PVA, 27 000 Da). This approach relies on the discovery that as low as 1% PVA can prevent precipitation of the growing melanin polymer thus allowing investigation of the chromophoric phases accompanying oxidation of DHI without confounding scattering effects. Spectrophotometric monitoring showed the initial development of a band around 530 nm persisting for about 1 h before gradually changing into the typical broadband spectrum of eumelanin. Reductive treatment caused a significant absorbance decrease in the visible region without affecting an absorption band around 320 nm. Initial product analysis indicated an altered formation ratio of 2,4′‐biindolyl (2) and 2,7′‐biindolyl (3) relative to control experiments. Overall, these results demonstrate for the first time that the development in solution of visible chromophores since the early oligomer stages is independent of strong aggregation/precipitation phenomena.
• 5,6-Dihydroxyindole Tetramers with “Anomalous” Interunit Bonding Patterns by Oxidative Coupling of 5,5‘,6,6‘-Tetrahydroxy-2,7‘-biindolyl:  Emerging Complexities on the Way toward an Improved Model of Eumelanin Buildup
  作者：Alessandro Pezzella、Lucia Panzella、Anna Natangelo、Marianna Arzillo、Alessandra Napolitano、Marco d'Ischia

  DOI：10.1021/jo701652y

  日期：2007.11.1

  [Graphics]Chemical or enzymatic oxidation of 5,6-dihydroxyindole (1) leads to the rapid deposition of a black solid resembling eumelanin pigments by way of a complex oligomerization/polymerization process that proceeds in the early stages via dimers 2-3 and trimers 5-6 characterized by 2,4'- and 2,7'-couplings. Despite extensive efforts, the structures of the higher oligomers, which define the structural architecture and physicochemical properties of the eumelanin particles, have so far defied elucidation. Using a dimerdimer coupling strategy that has recently allowed the first successful entry to a tetramer of 1, we report now three additional tetramers obtained by oxidation of 5,5',6,6'-tetrahydroxy-2,7'-biindolyl (3) with the peroxidase/H2O2 system. On the basis of extensive 2D NMR and mass spectrometric analysis, the products were identified as 5,5',5 '',5 ''',6,6',6 '',6 '''-octaacetoxy-7,2': 3',3 '': 2 '',7 '''-tetraindolyl (acetylated 8, 3%), 5,5',5 '',5 ''',6,6',6 '',6 '''-octaacetoxy-2,7': 4',4 '': 7 '',2 '''-tetraindolyl (acetylated 9, 4%), and 5,5',5 '',5 ''',6,6',6 '',6' octaacetoxy-2,7': 2',3 '': 2 '',7 '''-tetraindolyl (acetylated 10, 5%), in which the inner units are linked through unexpected 3,3'-, 4,4'-, and 2,3'-linkages. If verified in further studies, the newly uncovered coupling patterns would entail important consequences for current models of eumelanin structure based on one-dimensional structural chains with extended 7-electron conjugation or,pi-stacked flat oligomer aggregates.