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Juyeol Lee Soyeong Kang Jungjoon Kim Dohyun Moon Young Ho Rhee 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(2):638-641
A de novo synthetic strategy for the production of oligosaccharides containing 2,3,6‐trideoxypyranoglycoside is reported. The key event is the Pd‐catalyzed asymmetric diastereoselective hydroalkoxylation of ene‐alkoxyallene‐linked glycosidic fragments. The utility of this approach was demonstrated by the activation‐free, stereodivergent, and convergent synthesis of various 2‐deoxyoligosaccharides, as well as their aglycon conjugates. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(38):11742-11746
Reported herein is an efficient copper(I)‐catalytic system for the diastereo‐ and enantioselective 1,2‐addition of 1,1‐bis[(pinacolato)boryl]alkanes to protected imines to afford synthetically valuable enantioenriched β‐aminoboron compounds bearing contiguous stereogenic centers. The reaction exhibits a broad scope with respect to protected imines and 1,1‐bis[(pinacolato)boryl]alkanes, thus providing β‐aminoboronate esters with excellent diastereo‐ and enantioselectivity. The synthetic utility of the obtained β‐aminoboronate ester was also demonstrated. 相似文献
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Ivan A. Gagarinov Tiehai Li Na Wei Javier Sastre&#x;Torao Robert P. de&#x;Vries Margreet A. Wolfert Geert‐Jan Boons 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(31):10657-10662
We describe a chemoenzymatic strategy that can give a library of differentially fucosylated and sialylated oligosaccharides starting from a single chemically synthesized tri‐N‐acetyllactosamine derivative. The common precursor could easily be converted into 6 different hexasaccharides in which the glucosamine moieties are either acetylated (GlcNAc) or modified as a free amine (GlcNH2) or Boc (GlcNHBoc). Fucosylation of the resulting compounds by a recombinant fucosyl transferase resulted in only modification of the natural GlcNAc moieties, providing access to 6 selectively mono‐ and bis‐fucosylated oligosaccharides. Conversion of the GlcNH2 or GlcNHBoc moieties into the natural GlcNAc, followed by sialylation by sialyl transferases gave 12 differently fucosylated and sialylated compounds. The oligosaccharides were printed as a microarray that was probed by several glycan‐binding proteins, demonstrating that complex patterns of fucosylation can modulate glycan recognition. 相似文献
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Fei Yu Jiayi Li Paul M. DeMent Yi‐Jung Tu H. Bernhard Schlegel Hien M. Nguyen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(21):7031-7035
Carbohydrates are essential moieties of many bioactive molecules in nature. However, efforts to elucidate their modes of action are often impeded by limitations in synthetic access to well‐defined oligosaccharides. Most of the current methods rely on the design of specialized coupling partners to control selectivity during the formation of glycosidic bonds. Reported herein is the use of a commercially available phenanthroline to catalyze stereoretentive glycosylation with glycosyl bromides. The method provides efficient access to α‐1,2‐cis glycosides. This protocol has been performed for the large‐scale synthesis of an octasaccharide adjuvant. Density‐functional theory calculations, together with kinetic studies, suggest that the reaction proceeds by a double SN2 mechanism. 相似文献