and 17, respectively). Ring closure of 15 and 17 in the presence of sodium carbonate gave 5 and 22, respectively. By contrast, glycosylation of the sodium salt of 6 with 2,3,5-tri-O-benzoyl-D-ribofuranosyl bromide (11) or the persilylated 6 with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose gave mainly the N-2 glycosylated derivative 13, which on ammonolysis and ring closure furnished 18. Phosphorylation
6-
氨基-1-(2-脱氧-β-D-
氨基-
呋喃呋喃糖基)
吡唑并[4,3 - c ]
吡啶-4(5 H)-一(5)以及2-(β-D-合成了6-
氨基
吡唑并[4,3 - c ]
吡啶-4(5 H)-一(分别为18和22)的
核糖呋喃糖基)-和2-(2-脱氧-β-D-核
呋喃糖基)-衍
生物。
吡唑核苷前体的碱催化的闭环反应。甲基3(5)-cyanomethylpyrazole -4-
羧酸乙酯(的钠盐的糖基化6与1-
氯-2-脱氧-3,5-二- )ø - p
甲苯甲酰-α-D-赤-pentofuranose(8)提供了相应的N-1和N-2糖基衍
生物(分别为9和10)。用
甲醇钠对9和10进行脱苯甲酰化,分别得到去保护的核苷14和16。14和16的进一步
氨解得到5(或3)-
氰基甲基-1-(2-脱氧-β-D-赤型-五
呋喃糖基)
吡唑-4-羧酰胺(分别为15和17)。在
碳酸钠存在下15和17的闭环反应得到5和22, 分别。相比之下,钠盐的糖基化6与2