由无水AlCl(3)和H(2)O以3:1比例原位形成的酸性试剂比四氢呋喃中Me(3)N x BH(3)还原环亚苄基乙缩醛的效率高得多单独的AlCl(3)。在提出的条件下,己吡喃糖苷的二恶烷型4,6-O-亚苄基乙缩醛以优异的产率选择性地给出相应的4-羟基,6-O-苄基衍生物。半乳糖吡喃糖苷的二氧戊环型3,4-O-亚苄基乙缩醛的还原开口也非常有效且具有区域选择性,可生成3-O-苄基衍生物(来自3,4-O-外亚苄基乙缩醛)或4-O-苄基衍生物(来自3,4-O-内-亚苄基缩醛)取决于缩醛碳原子的构型。
Synthesis of Fragments of the Glycocalyx Glycan of the ParasiteSchistosoma mansoni
摘要:
The chemical synthesis of alpha-L-Fucp-(1 --> 3)-beta-D-GalpNAc-(1 --> 4)-beta-D-GlcpNAc-(1 --> 3)-alpha-D-GalpO(CH2)(5)NH2, beta-D-GalpNAc-(1 --> 4)-[alpha-L-Fucp-(1 --> 3)-]beta-D-GlcpNAc-(1 --> 3)-alpha-D-GalpO(CH2)(5)NH2, and alpha-L-Fucp-(1 --> 3)-beta-D-GalpNAc-(1 --> 4)- [alpha-L-Fucp-(1 --> 3)-]beta-D-GlcpNAc-(1 --> 3)-alpha-D-GalpO(CH2)(5)NH2 is described. These structures represent fucosylated oligosaccharide fragments of the glycocalyx glycan of the cercarial stage of the parasite Schistosoma mansoni, and in protein-conjugated form they are potential diagnostics in the search for antibodies raised against the glycan in the serum of infected humans.