Significant Substituent Effect on the Anomerization of Pyranosides: Mechanism of Anomerization and Synthesis of a 1,2-<i>cis</i>Glucosamine Oligomer from the 1,2-<i>trans</i>Anomer
作者:Shino Manabe、Hiroko Satoh、Jürg Hutter、Hans Peter Lüthi、Teodoro Laino、Yukishige Ito
DOI:10.1002/chem.201303474
日期:2014.1.3
Aminoglycosides containing a 2,3‐trans carbamate group easily undergo anomerization from the 1,2‐trans glycoside to the 1,2‐cis isomer under mild acidic conditions. The N‐substituent of the carbamate has a significant effect on the anomerization reaction; in particular, an N‐acetyl group facilitated rapid and complete α‐anomerization. The differences in reactivity due to the various N‐substituents were
在弱酸性条件下,含有2,3-反式氨基甲酸酯基团的氨基糖苷很容易从1,2-反式糖苷变为1,2-顺式异构体。氨基甲酸酯的N-取代基对异构化反应有显着影响。特别是,N-乙酰基促进了快速和完全的α-异构化。DFT计算的结果支持了由于各种N取代基引起的反应性差异。发现乙酰基羰基的接近异头位置的方向显着地促进了异构化反应的进行。通过利用该反应,可形成具有多个1,2-顺式的低聚氨基糖苷糖苷键是通过一个步骤从1,2-反式糖苷生成的。