Amino acid catalyzed direct enantioselective formation of carbohydrates:: one-step de novo synthesis of ketoses

The amino acid-catalyzed direct enantioselective one-step de novo synthesis of carbohydrates using dihydroxyacetone phosphate mimetics as donors and aldehydes or in situ generated imines as acceptors is presented. The addition of water significantly accelerates as well as improves the enantioselectivity of the biomimetic aldol and Mannich reactions. The C-3+C-n methodology presented herein is a direct entry to orthogonally protected C-5 and C-6 ketoses (e.g., ribulose, tagatose and piscose) and deoxy- and aminosugars such as 4-amino-4-deoxy-fructose. (c) 2005 Elsevier Ltd. All rights reserved.