Glycoside-clustering round calixarenes toward the development of multivalent ligands. Synthesis and conformational analysis of Calix[4]arene O- and C-glycoconjugates |
| |
Authors: | Dondoni Alessandro Kleban Martin Hu Xubo Marra Alberto Banks Harold D |
| |
Institution: | Dipartimento di Chimica, Laboratorio di Chimica Organica, Università di Ferrara, 44100 Ferrara, Italy. adn@dns.unife.it |
| |
Abstract: | Bis- and tetra-O- and C-glycosyl calixarenes (calixsugars) have been prepared by tethering carbohydrate moieties to a tetrapropoxycalix4]arene scaffold through alkyl chains. Two methodologies have been employed. One consisted of the stereoselective multiple glycosylation of upper rim calix4]arene polyols leading to calix-O-glycosides; the other involved a multiple Wittig olefination of upper rim calix4]arene-derived polyaldehydes by the use of sugar phosphoranes and reduction of the alkene double bonds affording calix-C-glycosides. The NMR spectra and NOE experiments of bis-glycosylated products indicate that compounds bearing sugar-protected residues exist preferentially in solution in a flattened cone arrangement (far conformation) whereas deprotected derivatives adopt a close conformation. Calculations by molecular mechanics of the latter compounds point to a close conformation as well in gas phase. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |