Alkaline solutions of 6, 7-dimethyllumazines substituted at position 8 with groups bearing a 2'-hydroxyl group exhibit no long wavelength absorption; analogs without a 2'-hydroxyl group show absorption in the visible range. In HtO, at alkaline pH, analogs with a 2'-hydroxyl substituent show nmr absorption of the 7-methyl group at-1.37 ppm, while the &methyl group exhibits singlets at-2.17 and-2.07 ppm. Analogs lacking the 2'-hydroxyl group do not ...
