ISSN:
1573-1111
Keywords:
Cyclodextrin
;
transacylation
;
metal
;
Cu(II)
;
catalysis
;
ester
;
supramolecule
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The paper reports the synthesis of aβ-cyclodextrin (β-CD) derivative (1) functionalized with a ligand subunit at the secondary-hydroxyl rim. The ligand subunit is 2-hydroxymethyl-6-thiomethyl pyridine connected to the macrocycle via a thioether bond. In the presence of Cu(II) ions1 accelerates the cleavage of thep-nitrophenyl esters of picolinic acid (PNPP), quinaldic acid (PNPQ) and its 6-phenyl derivative (PNPQPh) via the nucleophilic attack of the hydroxyl of the pyridine subunit. However, theβ-CD derivative is less effective than the ligand 2-hydroxymethyl-6-methylthiomethyl pyridine (2), indicating no cooperation between the hydrophobic and metal ion recognition sites. However, in the case of PNPQPh, the observed rate constants in the presence of Cu(II) ions are close to that of model2 and this suggests we are approaching a binding mode appropriate for taking advantage of the two binding sites of the metal receptor1 · Cu(II). Interestingly, the most reactive derivative with nativeβ-CD is thep-nitrophenyl quinaldate (PNPQ) in accord with its mode of complexation to the macrocycle and the location of the actual nucleophile (one of the secondary hydroxyls ofβ-CD).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01045981
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