Pyrazolopyrimidine Nucleosides. 9. Studies of the Isomeric N-Methylformycins

Article abstract of DOI:10.1021/ja00528a050

The syntheses of 4-methylformycin (7) and 6-methylformycin (8) are described.Structural assignements if 7 and 8 were based on UV, 1H NMR, and 13C NMR data.N-7-Methylformycin (9) was resynthesized by an alternative route and comparisons of the physicochemical properties of all five of the mono-N-methylformycins are presented. 6-Methylformycin (8) was found to be unstable in aqueous solution yielding three products, formycin B (2), N-7-methylformycin (9), and 6-methylformycin B (10). 6-Methylformycin B (10), 4-methylformycin B (11), and 1-methylformycin B (12) were prepared by a reaction of nitrosyl chloride with 8, 7, and 1-methylformycin (3), respectively.