抄録
Autoxidative cleavage of N-p-tolyl-D-glucosylamine (I) in ethanol solution containing p-toluidine yielded three pigments, X1, X3, and X3, which were isolated together with other decomposition products. These pigments were identified with 2, 3-dideoxo-2, 3-di(p-tolylimino)-5-methylindoline (X1) (reddish brown), 5, 5'-dimethylindirubin (X2)(violet), and 3-deoxo-3-(p-tolylimino)-5, 5'-dimethylindirubin (X3) (violet). These pigments were formed from the C1 -C2 fragment of the sugar and p-toluidine, and their structure was identified by synthesis from 5-methylisatin (X) by a different route. Free radical signal was detected in the electron spin resonance spectrum of the rection mixture of I and p-toluidine, and the signal was retained during the browning reaction which required a large amount of oxygen at the initial stage of the reaction. These results indicate that a free radicald formation was involved in this amino-carbonyl reaction and, therefore, the pigments obtained here were formed from C1-C2 fragments produced by the radical reaction between the sugar and the amine.
