Search for a simpler synthetic model system for intramolecular 1,3-dipolar cycloaddition to the 5,6-double bond of a pyrimidine nucleoside

摘要: Abstract In search for a simpler model system the study of intramolecular thermal reactions between base and 5'-functionalized sugar moiety in nucleosides, 1-(3-azidopropyl)uracil (2), 1-(4-azidobutyl) pyrimidines (12 13) 1-(5-azidopentyl)-uracil (14) was synthesized through corresponding ω-benzoyloxy-(6,7 8) ω-hydroxyalkyl-pyrimidines (9,10 11). Heating 2 gave 1,N6-trimethylene-6-aminouracil (4), while heating 12 13 N1-C6 cleaved addition products. 15 16, respectively. regiospecifically transformed to 1,2,3-triazole derivatives, 17,18 19. 1-(4-azidobutyl)-5-bromouracil (20) yielded 3,9-tetramethylene-8-azaxanthine (22). 9 with NBA 1,06-tetramethylene-5-bromo-6-hydroxy-5,6-dihydrouracil (24) 5-brominated analog (25). The 4-functionalized butyl side chain proved serve as substitute pyrimidine ribonucleosides.