Synthesis of aromatic Amadori compounds

Article abstract of DOI:10.1016/0008-6215(91)84043-E

A series of O-isopropylidene protected aromatic Amadori compounds [N-(1-deoxy-D-fructos-1-yl)-L-amino acid esters] were synthesized by reacting 2,3:4,5-di-O-isopropylidene-1-O-(trifluoromethanesulfonyl)-D-fructopyra nose with alkyl esters of L-phenylalanine, L-tyrosine, and L-tryptophan. The Amadori compounds were obtained in much higher yields than those previously reported due to utilizing triflate as an extremely reactive leaving group at C-1 of the sugar reagent. The triflate derivative was prepared in high yield using the sterically hindered, non-nucleophilic base, 2,6-di-tert-butyl-4-methylpyridine, as proton acceptor. The Amadori compounds were characterized by ¹H- or ¹³C-n.m.r. spectroscopy, as well as by i.r. and mass spectroscopy. ¹³C-n.m.r. spectroscopy was used to study the equilibria among the various ring forms of the free-hydroxy D-fructose-tryptophan compound.