Thiourea-linked upper rim calix[4]arene neoglycoconjugates: synthesis, conformations and binding properties

Org Biomol Chem. 2003 May 21;1(10):1802-9. doi: 10.1039/b301595e.

Abstract

The thiourea group has been exploited to link two or four carbohydrate units at the upper rim of tetrapropoxycalix[4]arene derivatives in the cone conformation. Two synthetic methodologies were used, the first one consisting of the condensation of di- and tetraminocalix[4]arenes with the isothiocyanate of monosaccharides in dry CH2Cl2 at room temperature and the second one exploiting the condensation of an aminolactoside with a calixarene isothiocyanate. The first method allows the glycoconjugates to be obtained in 75-80% overall yields. The disfunctionalized derivatives exist in a closed flattened cone conformation in CDCl3 and CD3OD due to the formation of intramolecular hydrogen bonds involving the thiourea groups which are broken in DMSO-d6 to give an open flattened cone conformation. The thiourea groups act not only as linkers but also as binding units for anionic substrates as evidenced by solution 1H NMR and ESI-MS experiments. Turbidimetric analysis indicates that the tetraglucoside and tetragalactoside clusters give specific interactions with Concanavalin A (Con A) and peanut lectin (PNA), respectively. Both features show that the neoglycoconjugates could also be used as site specific molecular delivery systems.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Calixarenes*
  • Concanavalin A / metabolism
  • Glycoconjugates / chemical synthesis
  • Glycoconjugates / chemistry*
  • Glycoconjugates / metabolism*
  • Hydrogen Bonding
  • Molecular Conformation
  • Nephelometry and Turbidimetry
  • Organophosphorus Compounds / chemistry
  • Organophosphorus Compounds / metabolism
  • Peanut Agglutinin / metabolism
  • Phenols / chemistry*
  • Spectrometry, Mass, Electrospray Ionization
  • Substrate Specificity
  • Thiourea / chemistry*

Substances

  • Glycoconjugates
  • Organophosphorus Compounds
  • Peanut Agglutinin
  • Phenols
  • calix(4)arene
  • Concanavalin A
  • Calixarenes
  • Thiourea