Abstract Alkylation of 3-alkyl-6-methyl-5, 7-dioxo-4, 5, 6, 7-tetrahydro-1, 2, 3-triazolo [4, 5-d] pyrimidines I with alkyl halides in dimethylformamide in the presence of potassium carbonate, or by analogous alkylation of sodium salts of compounds I afforded the respective 4-alkyl derivatives III but not 5-alkyloxy-3-alkyl-6-methyl-7-oxo-6, 7-dihydro-1, 2, 3- triazolo [4, 5-d] pyrimidines IV or isomeric 1, 3-dialkyl-6-methyl-5, 7-dioxo-4, 5, 6, 7- ...
