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目的获取具有1,2-顺式半乳糖苷键的带有易于选择性脱除的保护基的二糖半乳糖基(α1→2)葡萄糖片段。方法以D-半乳糖和D-葡萄糖为原料,采用多种保护方法与偶联策略,合成保护的二糖甲基-2-O-苯甲酰基-3-O-烯丙基-4,6-O-苯亚甲基-α-D-半乳吡喃糖基-(1→2)-3,4,6-三-O-苯甲酰基-α-D-葡萄吡喃糖苷(11)。结果来源于D-葡萄糖的甲基-4,6-O-苯亚甲基-α-D-葡萄吡喃糖苷依次通过选择性乙酰化、苯甲酰化、脱苯亚甲基、苯甲酰化、选择性脱乙酰基,得到甲基-3,4,6-三-O-苯甲酰基-α-D-葡萄吡喃糖苷。由D-半乳糖所合成的供体异丙基-2-O-苯甲酰基-3-O-烯丙基-4,6-O-苯亚甲基-β-D-1-硫代半乳吡喃糖苷与受体甲基-3,4,6-三-O-苯甲酰基-α-D-葡萄吡喃糖苷偶联,获得了甲基-2-O-苯甲酰基-3-O-烯丙基-4,6-O-苯亚甲基-α-D-半乳吡喃糖基-(1→2)-3,4,6-三-O-苯甲酰基-α-D-葡萄吡喃糖苷和甲基-2-O-苯甲酰基-3-O-烯丙基-4,6-O-苯亚甲基-β-D-半乳吡喃糖基-(1→2)-3,4,6-三-O-苯甲酰基-α-D-葡萄吡喃糖苷,α-半乳糖苷键联接与β-半乳糖苷键联接的立体选择性达到了3∶1,所有产物经NMR、MS等确证。结论首次完成了保护的二糖半乳糖基(α1→2)葡萄糖片段甲基-2-O-苯甲酰基-3-O-烯丙基-4,6-O-苯亚甲基-α-D-半乳吡喃糖基-(1→2)-3,4,6-三-O-苯甲酰基-α-D-葡萄吡喃糖苷的立体选择性合成。
Objective To obtain disaccharide galactosyl (α1 → 2) glucose fragments with a readily selective removable group with 1,2-cis galactoside linkages. Methods D-galactose and D-glucose as raw materials, using a variety of protection methods and coupling strategies, the synthesis of protected disaccharide methyl-2-O-benzoyl -3-O-allyl-4,6 -O-benzylidene-α-D-galactopyranosyl- (1 → 2) -3,4,6-tri-O-benzoyl-α-D-glucopyranoside (11) . As a result, the methyl-4,6-O-benzylidene-α-D-glucopyranoside derived from D-glucose was sequentially converted by selective acetylation, benzoylation, Selective deacetylation affords methyl-3,4,6-tri-O-benzoyl-α-D-glucopyranoside. Isopropyl-2-O-benzoyl-3-O-allyl-4,6-O-benzylidene-β-D-1-thio-half synthesized from D-galactose Coupling of the lactopyranoside to the acceptor methyl-3,4,6-tri-O-benzoyl-α-D-glucopyranoside yielded methyl-2-O-benzoyl-3- O-allyl-4,6-O-benzylidene-α-D-galactopyranosyl- (1 → 2) D-pyranopyranoside and methyl-2-O-benzoyl-3-O-allyl-4,6-O-benzylidene-β-D- galactopyranosyl- (1 → 2) Stereoselectivity of -3,4,6-tri-O-benzoyl-α-D-glucopyranoside, α-galactoside linkage to β-galactoside linkage reached 3: 1, all products confirmed by NMR, MS and so on. Conclusions For the first time, the protected disaccharide galactosyl (α1 → 2) glucose fragment methyl-2-O-benzoyl-3-O-allyl-4,6-O-benzylidene- Stereoselective Synthesis of D-galactopyranosyl- (1 → 2) -3,4,6-tri-O-benzoyl-α-D-glucopyranoside.