Synthesis of 6-Azapurines by Transformation of Toxoflavins and Reumycins (7-Azapteridines) and their Cytotoxicities

Abstract

This paper describes a reliable and facile synthesis of 6-azapurines, 1,5-dimethyl-1H-imidazo[4,5-e][1,2,4]triazin-6(5H)-ones and 5-methyl-5H-imidazo[4,5-e][1,2,4]triazin-6(7H)-ones, by treatment of toxoflavins and reumycins with 10 % aqueous or ethanolic sodium hydroxide at 5–70°C or reflux, followed by decarboxylation and oxidation by air along with a benzilic acid type rearrangement. Furthermore, heating the produced 6-azapurines in 10 % ethanolic sodium hydroxide afforded the corresponding 1-methyl-5,6-dioxo-1,4,5,6-tetrahydro-1,2,4-triazines with 1-methylurea. The antitumour activities of the 6-azapurines against CCRF-HSB-2 (human T-cell acute lymphoblastoid leukemia) and KB (human oral epidermoid carcinoma) cell lines were also investigated in vitro and some of the compounds showed prospective antitumour activities.