A high chemical reactivity of 5-azidouracils and its synthetic application: Novel synthesis of 8-substituted 1,3-dimethylxanthine derivatives

Article abstract of DOI:10.3987/COM-97-S68

A novel method for the preparation of 8-substituted 1,3-dimethylxanthine derivatives (7 or 8) is described: treatment of 6-alkylamino-5-bromo-1,3-dimethyluracils (6a-e), easily prepared by brornination of the corresponding 6-alkyIamino-1,3-dimethyluracils (5), with sodium azide in DMF at ambient temperature allowed the direct formation of the 8-substituted 1,3-dimethylxanthines (7) proceeding via a transient formation of the corresponding 5-azido-1,3-dimethyluracils. The 5-bromo-1,3-dimethyluracils (6f, g) possessing an α-branched alkylamino group at the 6-position similarly react with sodium azide to afford 8,8-disubstituted 1,3-dimethyl-8H-xanthines (8,8-disubstituted 1,3-dimethyl-3,8-dihydropurine-2,6-diones)(8).