Department of Chemistry and Biochemistry and School of Green Chemistry and Engineering, The University of Toledo, Toledo, OH, 43606, USA.
Department of Natural Sciences, University of Michigan-Dearborn, Dearborn, MI, 48128, USA.
Angew Chem Int Ed Engl. 2016 Apr 4;55(15):4767-71. doi: 10.1002/anie.201600488. Epub 2016 Mar 7.
A new and efficient approach for direct and stereoselective synthesis of β-mannopyranosides by anomeric O-alkylation has been developed. This anomeric O-alkylation of mannopyranose-derived lactols is proposed to occur under synergistic control of a kinetic anomeric effect and metal chelation. The presence of a conformationally flexible C6 oxygen atom in the sugar-derived lactol donors is required for this anomeric O-alkylation to be efficient, probably because of its chelation with cesium ion. In contrast, the presence of a C2 oxygen atom plays a minor role. This glycosylation method has been successfully utilized for the synthesis of the trisaccharide core of complex N-linked glycans.
开发了一种新的、有效的方法，通过端基 O-烷基化来直接、立体选择性地合成β-甘露糖苷。该方法提出，甘露糖衍生的内半缩醛的端基 O-烷基化是协同动力学端基效应和金属螯合控制的结果。糖衍生的内半缩醛供体中具有构象柔性的 C6 氧原子，可能因为其与铯离子螯合，对于高效的端基 O-烷基化是必需的。相比之下，C2 氧原子的存在则起着次要的作用。这种糖基化方法已成功用于合成复杂 N-连接聚糖的三糖核心。
