Synthesis and conformational analysis of novel water soluble macrocycles incorporating carbohydrates, including a β-cyclodextrin mimic
摘要:
Rigid macrocyclic scaffolds based on carbohydrates have potential for the display of recognition groups with defined 3D structure and may have application in bioorganic and supramolecular chemistry. A series of water soluble macrocyclic structures containing two saccharide units was synthesised by ring closing metathesis of allyl and pentenyl glycosides derived from glucuronic acid. The 3D structure of the constrained systems was explored by NMR and computational methods. CD spectra were also recorded. On the basis of experimental observations we suggest that the carbohydrate presentation is constrained into a U-shape for the smaller ring size but can access an S-shape arrangement in the larger macrocycle. As an extension it is shown that the larger macrocycle displayed phenomena similar to beta-cyclodextrin (beta-CD). The binding of 8-anilino-1-naphthalenesulfonate (ANS) to beta-CD is detectable by reversal of quenching of the ANS emission spectrum and a similar reversal of quenching was observed when this macrocycle was added to a solution of ANS; this was further supported by NMR. Furthermore molecular modelling suggests that the macrocyclic scaffolding has potential for the development of peptidomimetics. (C) 2004 Elsevier Ltd. All rights reserved.
Metathesis of Structurally Preorganized Bivalent Carbohydrates. Synthesis of Macrocyclic and Oligomeric Scaffolds
摘要:
[GRAPHICS]Bivalent carbohydrate substrates for metathesis were synthesized from glucuronic acid and phenylene-1,4-diamine. The substrate secondary structure depends on whether secondary or tertiary amides are present, and this influences the course of the metathesis reaction leading to novel multivalent scaffolding. Molecular modeling suggests that a very rigid macrocyclic scaffold has potential for the development of alpha-helix peptidomimetics.