Journal ArticleDOI
Stereoselective palladium-catalyzed O-glycosylation using glycals
Hahn Kim,Hongbin Men,Chulbom Lee +2 more
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TLDR
The combination of the glycosylation and subsequent functionalization provides a novel entry to saccharides which are otherwise difficult to prepare and should make this method a useful tool in synthetic carbohydrate chemistry.Abstract:
A highly stereoselective palladium-catalyzed O-glycosylation reaction is described. The reaction of a glycal 3-acetate or carbonate with the zinc(II) alkoxide of acceptors establishes the glycosidic linkage under palladium catalysis to give rise to disaccharides as the product in good yields and with high stereoselectivity. In contrast to the Lewis acid mediated Ferrier procedure, the anomeric stereochemistry of this reaction is controlled by the employed ligand. Whereas the use of a complex of palladium acetate and 2-di(tert-butyl)phosphinobiphenyl as the catalyst results in the exclusive beta-glycoside formation, the same reaction using trimethyl phosphite ligand furnishes an alpha-anomer as the major product. The utility of the 2,3-unsaturation present in the resulting glycoside is demonstrated by the further transformations such as dihydroxylation, hydration, and hydrogenation reactions. Thus, the combination of the glycosylation and subsequent functionalization provides a novel entry to saccharides which are otherwise difficult to prepare. The broad scope of the process, mildness of the reaction conditions, and experimental simplicity should make this method a useful tool in synthetic carbohydrate chemistry.read more
Citations
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New principles for glycoside-bond formation.
Xiangming Zhu,Richard R. Schmidt +1 more
TL;DR: New principles for the formation of glycoside bonds are discussed and developments, mainly in the last ten years, that have led to significant advances in oligosaccharide and glycoconjugate synthesis have been compiled and are evaluated.
Journal ArticleDOI
Methods for 2-Deoxyglycoside Synthesis.
Clay S. Bennett,M. Carmen Galan +1 more
TL;DR: This Review covers classical approaches to deoxyglycoside synthesis, as well as more recently developed chemistry that aims to control the selectivity of the reaction through rational design of the promoter.
Journal ArticleDOI
Neue Prinzipien für die Bildung von glycosidischen Bindungen
Xiangming Zhu,Richard R. Schmidt +1 more
TL;DR: In this article, the authors discuss the role of Oligosaccharide and Glycokonjugate in biologischen systemen, erfordert immer neue and vor allem grosere Mengen dieser Molekule.
Journal ArticleDOI
Recent Advances in Transition Metal-Catalyzed Glycosylation
Matthew J. McKay,Hien M. Nguyen +1 more
TL;DR: Recent advancement is highlighted by examining strategies that employ transition metal catalysis in the synthesis of oligosaccharides and glycoconjugates, which are mild and effective for constructing glycosidic bonds with reduced levels of waste through utilization of sub-stoichiometric amounts of transition metals.
References
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Asymmetric Transition Metal-Catalyzed Allylic Alkylations.
TL;DR: The focus of this review is on the area of enantioselective transition metal-catalyzed allylic alkylations which may involve C-C as well as C-X (X ) H or heteroatom) bond formation.
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Recent progress in O-glycosylation methods and its application to natural products synthesis
Kazunobu Toshima,Kuniaki Tatsuta +1 more
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Novel Electron-Rich Bulky Phosphine Ligands Facilitate the Palladium-Catalyzed Preparation of Diaryl Ethers
Attila Aranyos,David W. Old,Ayumu Kiyomori,John P. Wolfe,and Joseph P. Sadighi,Stephen L. Buchwald +5 more
TL;DR: In this paper, a general method for the palladium-catalyzed formation of diaryl ethers is described, where electron-rich, bulky aryldialkylphosphine ligands, in which the two alkyl groups are either tert-butyl or 1-adamantyl, are the key to the success of the transformation.
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Adventures in Carbohydrate Chemistry: New Synthetic Technologies, Chemical Synthesis, Molecular Design, and Chemical Biology
TL;DR: The field of carbohydrate chemistry has occupied the minds and hearts of many scientists for over a hundred years and, as we enter the twenty-first century, it continues to be both vigorous and challenging.