| Abstract: | Condensation of 3,4-dichloro-6-[(trimethylsilyl)oxy] pyridazine ( 3 ) with 1-O-acetyl-2,3,5-tri-O-benzoyl-β- D -ribofuranose ( 4 ), by the stannic chloride catalyzed procedure, has furnished 3,4-dichloro-1-(2,3,5-tri-O-benzoyl-β- D -ribofuranosyl) pyridazin-6-one ( 5 ). Nucleophilic displacement of the chloro groups and removal of the benzoyl blocking groups from 5 has furnished 3-chloro-4-methoxy-, 3,4-dimethoxy-, 4-amino-3-chloro-, 3-chloro-4-methylamino-, 3-chloro-4-hydroxy-, and 4-hydroxy-3-methoxy-1-β- D -ribofuranosylpyridazin-6-one. An unusual reaction of 5 with dimethylamine is reported. Condensation of 4,5-dichloro-3-nitro-6-[(trimethylsilyl)oxy]pyridazine with 4 yielded 4,5-dichloro-3-nitro-1-(2,3,5-tri-O-benzoyl-β- D -ribofuranosyl)pyridazin-6-one ( 24 ). Nucleophilic displacement of the aromatic nitro groups from 24 is discussed. Condensation of 3 with 3,5-di-O-p-toluoyl 2-deoxy- D -erythro-pentofuranosyl chloride ( 28 ) afforded an α, β mixture of 2-deoxy nucleosides. The synthesis of certain 3-substituted pyridazine 2′-deoxy necleosides are reported. |
