Calix[6]arene Derivatives Selectively Functionalized at Alternate Sites on the Smaller Rim with 2-Phenylpyridine and 2-Fluorenylpyridine Substituents to Provide Deep Cavities

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• 作者：Xianshun Zeng ; Andrei S. Batsanov ; Martin R. Bryce
• 刊名：Journal of Organic Chemistry
• 出版年：2006
• 出版时间：December 22, 2006
• 年：2006
• 卷：71
• 期：26
• 页码：9589 - 9594
• 全文大小：215K
• 年卷期：v.71,no.26(December 22, 2006)
• ISSN：1520-6904

文摘

The synthesis is described of calix[6]arene derivatives 4, 9, and 14 functionalized at alternate sites onthe smaller rim with 4'-(pyrid-2' '-yl)phenylmethoxy, (6'-phenylpyrid-3'-ylmethoxy), and {6'-[2-(9,9-di-n-hexylfluorenyl)]pyrid-3'-ylmethoxy} substituents, respectively. They were obtained by 3-fold reactionsof 2-[4-(bromomethyl)phenyl]pyridine (3), 5-(bromomethyl)-2-phenylpyridine (8), and 5-(bromomethyl)-2-(9,9-di-n-hexylfluorenyl)pyridine (13) with the 1,3,5-trimethylether of the t-Bu-calix[6]arene in thepresence of sodium hydride in THF in 56-75% yields. Detailed analysis of the ¹H NMR spectra (includingvariable-temperature data for 4) has established that 4, 9, and 14 exist predominantly in the C_3v coneconformation with minor C_s isomers also observed. The X-ray crystal structure of 4 reveals two moleculesof similar cone conformation, with all three 4'-(pyrid-2' '-yl)phenylmethoxy substituents stretched in theaxial direction. Molecule I has a dimeric capsule structure with (pyrid-2' '-yl)phenylmethoxy substituentsof one molecule interpenetrating those of its inversion equivalent to form a deep enclosed intermolecularcavity, which contains a CH₂Cl₂ guest molecule. Molecule II forms no such pair: the intramolecularcavity is filled with solvent molecules.