Unexpected formation of disulfide-based biscalix[4]arenes

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• 作者：Franti&scaron ; ek Stejskal^a ; Petra Cuří ; nov&aacute ; ^b ; Pavel Lhot&aacute ; k^a ; ^{lhotakp@vscht.cz" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Calixarene ; Bridging reaction ; Dimer formation ; Complexation ; Cation-π interactions ; Pyridinium guests
• 刊名：Tetrahedron
• 出版年：2016
• 出版时间：4 February 2016
• 年：2016
• 卷：72
• 期：5
• 页码：760-766
• 全文大小：623 K

文摘

Attempts at Pd-catalyzed bridging in sulfoxide-bearing calixarenes containing various substituents (phenyl, ethyl, pyrimidin-2-yl) gave the expected compound only in the case of the ethyl derivative. However, the reaction of sulfoxides with BuLi revealed the ability of the pyrimidin-2-yl group to function unexpectedly as a leaving group. This enabled, depending on the reaction conditions, preparation of unique bis-calixarenes connected together via two sulfur atoms spacers: –S–S–, –S(O)–S– or –S(O)₂–S–. As documented by ¹H NMR titrations these compounds, otherwise not easily accessible by common synthetic methods, showed recognition ability towards selected cations of the N-methylpyridinium type.