A novel method for functionalising resorcinarenes

Woodgate, Paul D.; Horner, Gillian; Maynard, N.Paul

doi:10.1016/s0040-4039(99)01338-6

Cited by 7 publications

(2 citation statements)

References 14 publications

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“…10,11 Resorcarene derivatives can be obtained through (i) functionalization of the two hydroxyl groups of the aromatic rings of the parent compound 12,13 or (ii) the introduction of suitable functionalities in the ortho position situated between the two OH groups of the aromatic rings. [14][15][16] On the basis of the latter approach, we have designed a resorcarene derivative with pendant arms containing sulfur donor atoms, namely, 5,11,17,-23-ethylthiomethylated calix [4]resorcarene, 1. The aim was to find a receptor able to complex toxic metal cations while discriminating against those which are known to play a significant role in biological processes, 17,18 such as alkali, alkaline-earth, and some transition metal cations.…”

Section: Introductionmentioning

confidence: 99%

“…Resorcarene derivatives can be obtained through (i) functionalization of the two hydroxyl groups of the aromatic rings of the parent compound , or (ii) the introduction of suitable functionalities in the ortho position situated between the two OH groups of the aromatic rings. − On the basis of the latter approach, we have designed a resorcarene derivative with pendant arms containing sulfur donor atoms, namely, 5,11,17,23-ethylthiomethylated calix[4]resorcarene, 1 . The aim was to find a receptor able to complex toxic metal cations while discriminating against those which are known to play a significant role in biological processes, , such as alkali, alkaline-earth, and some transition metal cations. , In this paper, we report the following: (i) the synthesis and characterization of 1 and its solubility in various solvents at 298.15 K. Given that the presence of two hydroxyl groups per monomer in the structure of 1 may lead to its dimerization or even polymerization of this ligand in aprotic media, partition experiments were carried out.…”

Section: Introductionmentioning

confidence: 99%

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Resorcarene-Based Receptor: Versatile Behavior in Its Interaction with Heavy and Soft Metal Cations

et al. 2006

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Standard solution Gibbs energies, DeltasG degrees, of the resorcarene-based receptor 5,11,17,23-ethylthiomethylated calix[4]resorcarene, (characterized by 1H NMR and X-ray diffraction studies) in its monomeric state (established through partition experiments) in various solvents are for the first time reported in the area of resorcarene chemistry. Transfer Gibbs energies of from hexane (reference solvent) to other medium are calculated. Agreement between DeltatG degrees (referred to the pure solvents) and standard partition Gibbs energies, DeltapG degrees (solvent mutually saturated) is found. Cation-ligand interactions were investigated through 1H NMR (CD3CN and CD3OD) and conductometric titrations in acetonitrile and methanol. 1H NMR data revealed the sites of interaction of with the metal cation. The composition of the metal-ion complexes (Ag+ and Pb2+ in acetonitrile and Ag+ and Cu2+ in methanol) was established through conductometric titrations. Thus, complexes of 1:1 stoichiometry were formed between and Ag+ and Pb2+ in acetonitrile and Cu2+ in methanol. However, in moving from acetonitrile to methanol, the composition of the silver complex was altered. Thus, two metal cations are hosted by a unit of the ligand. As far as Cu2+ and in acetonitrile is concerned, conductance data suggest that metalates are formed in which up to four units of Cu2+ are taken up per unit of resorcarene. The contrasting behavior of with Cu2+ in acetonitrile relative to methanol is discussed. As far as mercury (II) is concerned, the unusual jump in conductance observed in the titration of Hg2+ with in acetonitrile and methanol after the formation of a multicharged complex (undefined composition) is attributed to the presence of highly charged smaller units (higher mobility) resulting from the departure of pendant arms from the resorcarene backbone. Isolation of these species followed by X-ray diffraction studies corroborated this statement. The thermodynamic characterization of metal-ion complexes of Ag+ and Pb2+ in acetonitrile and Cu2+ and Ag+ in methanol is reported. Final conclusions are given.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Resorcarene-Based Receptor: Versatile Behavior in Its Interaction with Heavy and Soft Metal Cations

et al. 2006

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Mannich and O‐Alkylation Reactions of Tetraalkoxyresorcin[4]arenes – The Use of Some Products in Ligand‐Assisted Reactions

et al. 2006

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The measurement of the pKa of racemic tetramethoxyresorcin[4]arenes explains the failure to obtain good yields in attempted Mannich reactions of these substrates under classical reaction conditions. The failure is related to the lack of adequate concentrations of the iminium ions that results from the reduced acid strength of tetraalkoxyresorcin[4]arenes compared with that of the parent octahydroxyresorcin[4]arenes. However, the preparation of a series of Mannich bases derived from racemic tetraalkoxyresorcin[4]arenes was accomplished under microwave‐assisted aprotic reaction conditions and the use of preformed iminium ion intermediates. When the reactions were carried out with the use of chiral bis(aminol) ethers, mixtures of diastereomers were obtained that could be separated by flash chromatography. The absolute configurations of the enantiomerically pure tetrabenzoxazine derivatives were established in some cases by X‐ray crystallographic analysis and by a comparison of the nuclear magnetic resonance spectroscopic data. The alkylation of racemic tetramethoxyresorcin[4]arenes was achieved with the use of an excess of 2‐bromo‐N‐[(R)‐(+)‐(α‐methylbenzyl)]acetamide in acetonitrile containing potassium carbonate. Enantioselective ligand‐assisted reactions of aromatic aldehydes are also reported with the use of dialkylzinc reagents both in the absence and in the presence of terminal alkynes.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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