An alternative total synthesis of pentosidine

Pentosidine, a fluorescent advanced glycation endproduct that serves as a biomarker of diabetic complications, kidney dysfunction, oxidative stress, and aging and age-related diseases, was synthesized from 2,3-diaminopyridine and benzyloxycarbonyl (Cbz) protected chiral amino acids Nα-Cbz-lysine and Nδ-Cbz-ornithine. Regioselective alkylation of 2-(methylthio)imidazo[4,5-b]pyridine, chlorination of methylthio group, and amination of 2-chloro-imidazo[4,5-b]pyridine are the key steps. Hydantoin protection of amino acids was used and the deprotection under acidic condition was achieved in the presence of glycine. J. Heterocyclic Chem., (2011).