Synthesis and Properties of Condensed Lumazine-Ringsystems

Abstract

Abstract 1,3-Dimethyllumazine-6,7-diamine (1) and its monomethyl -(3,4) and monophenylamino (5) derivates are interesting starting materials for the synthesis of imidazo[4,5-g] (6-22) and pyrazino[2,3-g]lumazines (23-26). Ringclosure proceeds under relative drastic conditions and the resulting reaction products are highly fluorescent. Methylation of 5,7-dimethyll-imidazo[4,5-g)lumazine (6) led to an isomeric mixture of the 1- (17) and 3-methyl derivatives (7) which could be separated chromatographically. Their structural assignment was based on unambiguous syntheses heating 4 and 3, respectively, with formamide under reflux for ringclosure. The newly synthesized compounds have been characterized by 1H-NMR and UV-spectra as well as elemental analyses.