Conformational Mobility of the Bridged Calix[6]arenes with Allyl and Ethyl Groups at the Lower Rim
Conformational Mobility of the Bridged Calix[6]arenes with Allyl and Ethyl Groups at the Lower Rim
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下环具有烯丙基和乙基的桥联杯[6]芳烃的构象迁移率
DOI：
10.1246/bcsj.74.2167
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发表时间：
2001
影响因子：
4
通讯作者：
T. Kawashima
中科院分区：
文献类型：
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作者：
Shigehisa Akine;K. Goto;T. Kawashima
研究了下缘含烯丙基和乙基的桥联杯[6]芳烃的构象迁移率。四羟基化合物的烯丙基化得到两个异构体：5a（cone）和5 b（1，2，3-alternate），它们通过硅胶色谱分离。这些异构体在室温下经历缓慢异构化，半衰期约为2周。另一方面，发现乙基衍生物6-9在溶液中作为构象异构体的混合物存在;它们在NMR时间尺度上独立地观察到，但在实验室时间尺度上不可分割。6-9的两种异构体的比例取决于桥连单元上的官能度，通过分子力学计算研究了官能度的影响。在结晶状态下，具有溴官能团的乙基衍生物6被发现采取1，2，3-交替构象，而具有乙炔基的化合物7采取锥形构象。
The conformational mobility of the bridged calix[6]arenes with allyl and ethyl groups at the lower rim was investigated. Allylation of the tetrahydroxy compounds afforded two isomers: 5a (cone) and 5b (1,2,3-alternate), which were separated by silica-gel chromatography. These isomers underwent slow isomerization at room temperature with a half-life time of about 2 weeks. On the other hand, the ethyl derivatives 6–9 were found to exist as mixtures of conformational isomers in solution; they were observed independently on the NMR time-scale but were inseparable on the laboratory time-scale. The ratios of two isomers of 6–9 depended on the functionality on the bridging unit, the effects of which were investigated by molecular mechanics calculations. In the crystalline state, the ethyl derivative 6 with a bromo functionality was found to take the 1,2,3-alternate conformation, while compound 7 with an ethynyl group adopted the cone conformation.
博来霉素金属核心的重组
DOI：
--
发表时间：
2016
期刊：
影响因子：
--
作者：
Taha F. S. Ali;Satomi Ida;Yosuke Kanemaru;Ryoko Koga;Ayumi Tanaka;Akiyuki Hamasaki;Tomohiko Ejima;Mohamed Osman Radwan;Halil Ibrahim Ciftci;Hiromasa Kurosaki;Yoshinari Okamoto;Mikako Fujita;Masami Otsuka
通讯作者：
Masami Otsuka