Lanthanide(III) nitrobenzenesulfonates and p-toluenesulfonate complexes of lanthanide(III), iron(III), and copper(II) as novel catalysts for the formation of calix[4]resorcinarene

Karen Deleersnyder, Hasan Mehdi, István T. Horváth, Koen Binnemans, Tatjana N. Parac-Vogt

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Abstract

Lanthanide(III) salts of p-toluenesulfonic acid [lanthanide(III) tosylates, Ln(TOS)3] and nitrobenzenesulfonic acid [Ln(NBSA)3], and p-toluenesulfonate complexes of iron(III) and copper(II) were prepared, characterized, and examined as catalysts for the synthesis of resorcinol-derived calix[4]resorcinarenes. The reaction of resorcinol with benzaldehyde yields two isomers, the all-cis isomer (rccc) and the cis-trans-trans isomer (rctt) with the relative isomer ratios depending on the reaction conditions. However, in the reaction of resorcinol with octanal only one isomer, the all-cis isomer, is formed in high yields with less than 0.1 mol % of Yb(TOS)3. Examination of lanthanide(III) tosylates and lanthanide(III) nitrobenzenesulfonates revealed that ytterbium(III) 4-nitrobenzenesulfonate [ytterbium(III) nosylate, Yb(4-NBSA)3] and ytterbium(III) 2,4-dinitrobenzenesulfonate [Yb(2,4-NBSA)3] are the most active catalysts. The catalysts could be easily recovered and reused several times for resorcinarene formation without loss of efficiency. Surprisingly good results were also obtained with iron(III) and copper(II) p-toluenesulfonates. Besides optimizing the reaction conditions, new insights into the reaction mechanism were also obtained.

Original languageEnglish
Pages (from-to)9063-9070
Number of pages8
JournalTetrahedron
Volume63
Issue number37
DOIs
Publication statusPublished - Sep 10 2007

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Keywords

  • Catalysis
  • Lanthanides
  • Lewis acids
  • Macrocycles
  • Rare earths

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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