ZnCl2-mediated practical protocol for the synthesis of Amadori ketoses

An efficient and practical protocol for the synthesis of Amadori ketoses N-(1-deoxy-d-fructose-1-yl) amino acid (amino acid = l-valine (1), l-leucine (2), l-isoleucine (3), l-tryptophan (4), l-phenylalanine (5), l-arginine (6) has been accomplished by employing ZnCl2 as a catalyst. The developed method circumvents protection and deprotection steps as well as tedious ion-exchange and column chromatographic techniques. The accomplished Amadori ketoses showed moderate to weak angiotensin I converting enzyme (ACE) inhibitory activity.