C2-amidoglycosylation. Scope and mechanism of nitrogen transfer.
C2-amidoglycosylation. Scope and mechanism of nitrogen transfer.
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DOI：
10.1021/ja026281n
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发表时间：
2002-07
影响因子：
15
通讯作者：
Jing Liu;D. Gin
中科院分区：
文献类型：
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作者：
Jing Liu;D. Gin
报道了一锅法由糖基C2-酰胺基糖基化反应合成2-N-酰基-2-脱氧-β-吡喃糖苷。通过噻蒽-5-氧化物（11）和Tf 2 O的试剂组合活化糖供体，然后用酰胺亲核试剂和糖基受体处理，导致形成各种C2-酰胺基糖缀合物。C2-氮转移和糖苷键的形成都进行立体选择性，允许在C2处引入天然和非天然酰胺官能团，同时在一锅法中形成异头键。通过采用15 N-和18 O-同位素标记的低温NMR光谱法跟踪反应表明了一种机制，该机制涉及在这种新型氧化糖基化过程中形成C2-锍糖基亚氨酸盐39以及恶唑啉37作为关键中间体。
A one-pot C2-amidoglycosylation reaction for the synthesis of 2-N-acyl-2-deoxy-beta-pyranosides from glycals is described. Glycal donors activated by the reagent combination of thianthrene-5-oxide (11) and Tf2O, followed by treatment with an amide nucleophile and a glycosyl acceptor, lead to the formation of various C2-amidoglycoconjugates. Both the C2-nitrogen transfer and the glycosidic bond formation proceed stereoselectively, allowing for the introduction of both natural and nonnatural amide functionalities at C2 with concomitant anomeric bond formation in a one-pot procedure. Tracking of the reaction by low-temperature NMR spectroscopy employing 15N- and 18O-isotope labels suggests a mechanism involving the formation of the C2-sulfonium glycosyl imidate 39 as well as oxazoline 37 as key intermediates in this novel oxidative glycosylation process.