The synthesis and conformation of ß-cyclodextrins functionalised with enantiomers of Boc-carnosine

The synthesis of epimers 6-deoxy-6-[N-tert-butoxycarbony1-β-alanyl-(S)histidylamino]-β- cyclodextrin and 6-deoxy-6-[N-tert-butoxycarbonyl-β-alanyl-(R)histidylamino]-β- cyclodextrin is reported. CD and NMR spectroscopy reveals that in aqueous solution these compounds are arranged in a 'sleeping swan' like conformation. H bonds between the NH of peptide bonds and the upper rim of CDs stabilize self-inclusion. The chirality of His influences the orientation of the self-included chain in the cavity, thus determining different properties for the two epimers.