Abstract A series of the title compounds, 9-deazaxanthines, was regioselectively prepared in reasonable yields as major products from the reactions of 6-azidouracils 1a, b with stabilized ester-2a, b or keto-2c ylide phosphoranes and a moderated phosphorus ylide 3, instead of the expected triazoles. Side products were also observed wherein pyrimido [5, 4-g] pteridine- 2, 4, 5, 7-tetrone (15) and other fused ring systems or acyclic-substituted uracil derivatives ...