Tribenzotriquinacene-Based Crown Ethers: Synthesis and Selective Complexation with Ammonium Salts

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• 作者：Yu-Fei Zhang ; Xiao-Ping CaoHak-Fun Chow ; Dietmar Kuck
• 刊名：Journal of Organic Chemistry
• 出版年：2017
• 出版时间：January 6, 2017
• 年：2017
• 卷：82
• 期：1
• 页码：179-187
• 全文大小：542K
• ISSN：1520-6904

文摘

Two tribenzotriquinacene-based crown ethers, TBTQ-dibenzo-24-crown-8 5 and TBTQ-benzo-21-crown-7 6, were prepared from the key TBTQ intermediate, 2,3-dihydroxy-4b,8b,12b,12d-tetramethyltribenzotriquinacene (13), which in turn was synthesized in six steps using two variants of our cyclodehydration method on a multigram scale. The host–guest complexation properties of the TBTQ-based crown ethers 5 and 6 with a paraquat derivative, 16, and two secondary ammonium salts, 17 and 18, were studied by ¹H NMR spectroscopy and mass spectrometry. It was found that host 5 binds to the paraquat derivative 16 as a 1:1 complex in CDCl₃/CD₃CN solution with an association constant of K_a = (9.2 ± 1.8) × 10² M^–1, whereas no complexation was found for 17 and 18. In contrast, the TBTQ-crown ether 6 assembles selectively with dibutylammonium hexafluorophosphate 18 as a 1:1 complex in CDCl₃/CD₃COCD₃ [K_a = (5.0 ± 1.4) × 10² M^–1], for which a threaded [2]pseudorotaxane structure is assumed.