Polynuclear Heterocyclic Systems. XV. Dihydroquinoxalino[2,3-b]quinoxalines

Abstract

Fluoflavin has been found to have an absorption spectrum very similar to that of 5,12-dimethylquinoxalino[2,3-b]quinoxaline (I; R = R' = CH₃), and is assigned the structure 5,12-dihydroquinoxalino[2,3-b]quinoxaline (I; R = R' = H). Attempts to prepare 5,12-dimethylquinoxalino[2,3-b]quinoxaline from 2,3-dihydroxyquinoxaline and NN'-dimethyl-o-phenylenediamine resulted in the loss of a methyl group, and 5H-12-methylquinoxalino[2,3-b] was obtained. The same compound was also isolated following attempts to prepare 5,11-dimethylquinoxalino- [2,3-b]quinoxaline (II; R = R' = CH₃). The latter compound has not been obtained.