Catalyst-free, efficient, and green procedure for the synthesis of 5-heterocyclic substituted 6-aminouracils

In this paper, the results of our studies on the catalyst-free synthesis of some new 6-aminouracils bearing naphthoquinone, benzo[a]phenazine, benzo[f]pyrido[2,3-b]quinoxaline, and benzo[f]quinoxaline substituents are reported. At first, 6-amino-5-(3,4-dioxo-1-naphthalenyl)uracil derivatives were synthesized from the reaction of various 6-aminouracils with 1,2-naphthoquinone in DMSO at 70 °C in good to excellent yields. Subsequently, the prepared 6-amino-5-(3,4-dioxo-1-naphthalenyl)uracils were subjected to the condensation reaction with various vicinal diamines, in chloroform under reflux conditions to synthesize 6-aminouracils bearing benzo[a]phenazine, benzo[f]pyrido[2,3-b]quinoxaline, and benzo[f]quinoxaline derivatives.