Alkylation of 3-tert-Butylpyrimido[4′,5′:3,4]pyrazolo[5,1-c]-[1,2,4]triazine-4,10(1H,9H)-diones and -dithiones

The condensation of 7-amino-1-benzyl-3-tert-butyl-4-oxo-1,4-dihydropyrazolo[5,1-c][1,2,4]triazine-8-carbonitrile with formic acid afforded 1-benzyl-3-tert-butylpyrimido[4′,5′:3,4]pyrazolo[5,1-c][1,2,4]-triazine-4,10(1H,9H)-dione which was also synthesized by alkylation of 3-tert-butylpyrimido[4′,5′: 3,4]pyrazolo[5,1-c][1,2,4]triazine-4,10(1H,9H)-dione with benzyl chloride. The reactions of 1-benzyl- and 1-butyl-3-tert-butylpyrimido[4′,5′: 3,4]pyrazolo[5,1-c][1,2,4]triazine-4,10(1H,9H)-diones with butyl bromide and benzyl chloride, respectively, under harsh conditions gave substitution products at the N⁹ atom, the corresponding 1-benzyl-9-butyl and 9-benzyl-1-butyl derivatives. The alkylation of 3-tert-butyl pyrimido[4′,5′: 3,4]-pyrazolo[5,1-c][1,2,4]triazine-4,10(1H,9H)-dithione and its 8-methyl derivative in alkaline medium led to the formation of alkyl derivatives at the sulfur atom in the 10-position.