disaccharide 12 was also obtained by the reaction of 1,2,3,4-tetra-O-benzoyl-6-O-bromoacetyl-beta-D-galactopryanose (6) with 1 in the presence of trimethylsilyl trifluoromethane-sulfonate. Similarly, the trisaccharide 18 and the tetrasaccharide 20 were obtained by the treatment of 13, respectively, with 1 and 15, showing that, as with their 1-O-acetyl counterparts, beta-1-benzoates of saccharides bearing at O-2
甲基2,3,4-三-O-苯甲酰基-β-D-
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乳糖苷(1)的
溴乙酰化反应,然后用1,1-二
氯甲基甲基醚将生成的6-O-
溴乙酰基衍
生物2的甲氧基裂解,3,4-三-O-苯甲酰基-6-O-
溴乙酰基-α-D-
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乳糖基
氯(3)。
三氟甲磺酸银促进3与1的反应,得到甲基O-(2,3,4-三-O-苯甲酰基-6-O-
溴乙酰基-β-D-
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乳糖基)-(1 ---- 6)- 2,3,4-三-O-苯甲酰基-β-D-
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乳糖苷(12),在其非还原端基的O-6处带有可选择性除去的
溴乙酰基。将其O-脱
溴乙酰化,并将形成的二糖亲核试剂15再次用3处理,得到类似的三糖18。重复该反应序列,得到类似的四糖20,显示了逐步构建标题
寡糖的可行性。3与1,2,3,4-四-O-苯甲酰基-α-(7)和β-D-
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乳糖(5)的相似反应分别得到O-(2,3,4-tri-O-苯甲酰基-6-O-
溴乙酰基-β-D-
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乳糖基)-(1