Photoracemization and Deracemization of Biaryl Compounds

联芳基化合物的光外消旋化和去消旋化

• 批准号: 15550083
• 负责人: HATTORI Tetsutaro
• 金额: $ 2.5万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15550083/
• 关键词: atropisomerism; photoracemization; deracemization; 1,1'-biphenanthrene; blestriarene C; redox reaction; 1,1'-binaphthalene; nucleophilic aromatic substitution reaction; blestriarence C

In this study, we have synthesized blestriarene C (2,2',7,7'-tetrahydroxy-4,4'-dimethoxy-1,1'-biphenanthrene) and its analogs by using an ester-mediated nucleophilic aromatic substitution as a key step and investigated their photoracemization under fluorescent light exposure. Racemization of 1,1'-binaphthalenes and deracemization of blestriarene C were also examined.Blestriarene C was found to racemize by exposing its solution to the light near the ^1L_b absorption band. Removal of oxygen from the solution significantly retarded the reaction, suggesting intermediary of oxygen in the racemization. Blestriarene C analogs lacking 4,4'-dimethoxy and/or 7,7'-dihydroxy groups did not racemize under the conditions, while the 7,7'-diisopropoxy derivative, as well as the unsymmetrical biphenanthrene lacking 4'-methoxy and 7'-hydroxy groups, easily racemized. The tendency toward the racemization was found to strongly correlate with the redox potential of the compounds by cyclic voltammetry (CV) experiments. Thus, the lower redox potential the compound has, the higher racemization activity it shows. Based on these observations, we proposed a feasible reaction mechanism, which involves one-electron oxidation of blestriarene C by oxygen with the aid of the fluorescent light to form a radical cation intermediate. 1,1'-Binaphthalenes having two or three hydroxy and/or methoxy groups in total on each naphthalene half did not racemize under the same conditions. These compounds did not show reversible redox behavior on the CV spectra, which should be crucial in the photoracemization.

在本研究中，我们以酯介导的亲核芳香取代为关键步骤合成了blestriarene C（2,2',7,7'-四羟基-4,4'-二甲氧基-1,1'-联菲）及其类似物，并研究了它们在荧光照射下的光酰基化反应。还考察了1,1′-二萘的外消旋和壬二烯C的去消旋。通过将其溶液暴露在^1L_b吸收带附近的光下，发现Blestriarene C具有外消旋作用。从溶液中去除氧明显延缓了反应，表明氧在外消旋化过程中起到了中介作用。在此条件下，缺乏4,4'-二甲氧基和/或7,7'-二羟基的Blestriarene C类似物不发生外消旋，而7,7'-二异丙氧基衍生物以及缺乏4'-甲氧基和7'-羟基的不对称联苯则容易发生外消旋。通过循环伏安（CV）实验，发现化合物的外消旋化倾向与氧化还原电位密切相关。因此，化合物的氧化还原电位越低，其外消旋活性越高。基于这些观察，我们提出了一种可行的反应机理，即在荧光灯的辅助下，氧单电子氧化壬二烯C生成自由基阳离子中间体。在相同的条件下，在每个萘的一半上有两个或三个羟基和/或甲氧基的1,1'-联萘不会发生外消旋。这些化合物在CV光谱上没有表现出可逆的氧化还原行为，这在光消酰基化中是至关重要的。

项目成果

T.Hattori: "Synthesis, Resolution, and Absolute Stereochemistry of (-)-Blestriarence C"J.Org.Chem.. 68・6. 2099-2108 (2003)

T. Hattori：“(-)-Blestriarence C 的合成、解析和绝对立体化学”J.Org.Chem.. 68・6 (2003)。

Interconversion between syn and anti Conformations of 1,3-Bis(O-cyanomethyl)-p-tert-butylthiacalix[4]arene

• DOI: 10.1246/cl.2004.184
• 发表时间: 2004-01
• 期刊: Chemistry Letters
• 影响因子: 1.6
• 作者: V. Bhalla;Manoj Kumar;C. Kabuto;T. Hattori;S. Miyano

Stereoselective dialkylation of the proximal hydroxy groups of calix-and thiacalix[4]arenes.

杯-和硫代杯[4]芳烃的近端羟基的立体选择性二烷基化。

• 发表时间: 2004
• 期刊: Org.Biomol.Chem. 2(6)
• 作者: T.Ohmura;W Mori;H.Hiraga;M.Ono;Yuko NISHIMOTO;Hiroyuki Suga et al.;Masami Sakamoto;F.Narumi
• 通讯作者: F.Narumi

Epimerization of Diastereometric α-Amino Nitriles to Single Stereoisomers in the Solid State

非对映α-氨基腈差向异构化为固态单立体异构体

• 发表时间: 2004
• 期刊: Org.Lett. 6・13
• 作者: V.Bhalla;R.Sakurai
• 通讯作者: R.Sakurai

Synthesis of all stereoisomers of sulfinylcalix[4]arenes.

• DOI: 10.1021/jo026801x
• 发表时间: 2003-02
• 期刊: The Journal of organic chemistry
• 作者: Naoya Morohashi;H. Katagiri;Nobuhiko Iki;Yu Yamane;C. Kabuto;T. Hattori;S. Miyano