Macrocyclic Carbohydrate/Amino Acid Hybrid Molecules - Synthesis and Evaluation as Artificial Receptors
Abstract: Methods were developed for the synthesis of three different types of macrocyclic carbohydrate/amino acid hybrid molecules. In the synthesis of the first type of macrocycles, a glucosamine derivative was oxidized at C6 and the obtained sugar amino acid was coupled to tripeptides. The resulting hybrids were transformed into dimers and cyclized in a macrolactamization step to obtain C2-symmetric macrocycles. In the second type of macrocycles, the same sugar amino acid was used together with tyrosine to prepare a C3-symmetric macrocycle with alternating sugar amino acid and tyrosine residues. In the synthesis of the third type of macrocycles, Cu(I)-catalysed 1,3-dipolar cycloaddition of azides and acetylenes was employed to form C2-symmetric carbohydrate/amino acid hybrid molecules containing two 1,2,3-triazole units. The macrocycles that were water-soluble were screened for affinity towards biomolecules. Weak, but significant, affinity was found for dAMP, dGMP, serotonin and caffeine for some of the macrocycles (Ka approx. 10 M-1) which indicates that molecules of this type have potential as artificial receptors. Possibilities to extend the developed methods to prepare further types of macrocycles are discussed.
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