Formation of pyridinium betaines by reaction of hexoses with primary amines

The reaction of glucose or fructose with primary amines and the thermal deg radation of Amadori products of glucose leads to the formation of 6-formyl- 1-alkylpyridinium-3-olates (5), of which 6-formyl-1-propylpyridinium-3-olat e was isolated from a reaction mixture. A reference substance can be prepar ed in a two-step procedure from 5-(hydroxymethyl)-2-furaldehyde. Comparativ ely high yields of these betaines in relation to other W-absorbing products are obtained under typical food processing and physiological conditions. W ith primary amines, the betaines readily form a Schiff base that undergoes Strecker-type degradation when heated in aqueous solution. (C) 1998 Elsevie r Science Ltd. All rights reserved.