85917-82-4Relevant academic research and scientific papers
Glycosyl Vinylogous Carbonates as Glycosyl Donors by Metal-Free Activation
Kasdekar, Niteshlal,Walke, Gulab,Deshpande, Kshitij,Hotha, Srinivas
, p. 5472 - 5484 (2022/04/28)
Synthesis of glycoconjugates employs a glycosylation reaction wherein an electrophile and a nucleophile known as a glycosyl donor and an aglycon, respectively, are involved. Glycosyl donors often contain a leaving group at the anomeric carbon that upon reaction with activator(s) results in a highly reactive electrophilic species reported as an oxycarbenium ion contact pair that will then be attacked by the aglycon. Therefore, identification of the correct glycosyl donor and activation protocol is essential for the synthesis of all glycoconjugates. Recently identified [Au]/[Ag]-catalyzed activation of ethynylcyclohexyl glycosyl carbonates is one such versatile method for the synthesis of glycosides, oligosaccharides, and glycoconjugates. In this work, stable glycosyl vinylogous carbonates were identified to undergo glycosidation in the presence of a sub-stoichiometric quantity of TfOH. The reaction is fast and suitable for donors containing both C2-ethers and C2-esters. Donors positioned with C2-ethers resulted in anomeric mixtures with greater selectivity toward 1,2-cis glycosides, whereas those with C2-esters gave 1,2-trans selective glycosides. The versatility of the method is demonstrated by conducting the glycosylation with more than 25 substrates. Furthermore, the utility of the glycosyl vinylogous carbonate donors is demonstrated with the successful synthesis of the branched pentaarabinofuranoside moiety of the Mycobacterium tuberculosis cell wall.
Gold(III)-Catalyzed Glycosylation using Phenylpropiolate Glycosides: Phenylpropiolic Acid, An Easily Separable and Reusable Leaving Group
Shaw, Mukta,Thakur, Rima,Kumar, Amit
, p. 589 - 605 (2019/01/14)
An efficient and operationally simple gold(III)-catalyzed glycosylation protocol was developed using newly synthesized benchtop stable phenylpropiolate glycosyl (PPG) donors. Gold(III)-catalyzed activation of PPGs proceeds well with various carbohydrate a
Nucleofuge Generating Glycosidations by the Remote Activation of Hydroxybenzotriazolyl Glycosides
Neralkar, Mahesh,Mishra, Bijoyananda,Hotha, Srinivas
, p. 11494 - 11504 (2017/11/10)
Hydroxybenzotriazole is routinely used in peptide chemistry for reducing racemization due to the increased reactivity. In this article, very stable hydroxybenzotriazolyl glucosides were identified to undergo glycosidation. The reaction was hypothesized to go through the remote activation by the Tf2O at the N3-site of HOBt followed by the extrusion of the oxocarbenium ion that was attacked by the glycosyl acceptor. Further, equilibration of the zwitterionic benzotriazolyl species makes the leaving group noncompetitive and generates the nucleofuge that has been reconverted to the glycosyl donor. The reaction is mild, high yielding, fast and suitable for donors containing both C2-ethers and C2-esters as well. The regenerative-donor glycosidation strategy is promising as it enables us to regenerate the glycosyl donor for further utilization. The utility of the methodology for the oligosaccharide synthesis was demonstrated by the successful synthesis of the branched pentamannan core of the HIV1-gp120 complex.
Gold-catalysed glycosylation reaction using an easily accessible leaving group
Koppolu, Srinivasa Rao,Niddana, Ramana,Balamurugan, Rengarajan
supporting information, p. 5094 - 5097 (2015/05/13)
Gold(iii)-catalysed glycosylation reaction has been developed by employing a new and easily accessible leaving group synthesized from ethyl cyanoacetate. Several nucleophiles like alcohols, thiols, allyltrimethylsilane, trimethylsilyl azide and triethylsilane have been reacted to make the corresponding glycosides in good yields and with marginal to excellent α-selectivity. This journal is
Traceless Staudinger ligation of glycosyl azides with triaryl phosphines: Stereoselective synthesis of glycosyl amides
Bianchi, Aldo,Bernardi, Anna
, p. 4565 - 4577 (2007/10/03)
α-Glycosyl amides can be synthesized from the corresponding O-benzyl-α-glycosyl azides using a traceless Staudinger ligation with diphenylphosphanyl-phenyl esters 4. All the phosphines employed and their phenol precursors are stable to air at 4 °C for months. Fast intramolecular trapping of the reduction intermediates results in the direct formation of the amide link, which, in turn, prevents epimerisation and allows retention of configuration at the anomeric carbon. Yields and α-selectivity are high when the reaction is performed in polar aprotic solvents. Removal of the benzyl ether protecting groups is achieved by catalytic hydrogenation. α-Glycosyl amides represent a class of virtually unexplored nonhydrolyzable monosaccharide derivatives that may find a useful application as sugar mimics. Conformational studies by NMR spectroscopy confirm that deprotected α-glycosyl amides in the gluco, galacto, and fuco series retain the normal pyranose conformation of the monosaccharide. The reaction of phosphines 4 with tetra-O-acetyl-glycosyl azides is nonstereoconservative, and β-glycosyl amides are obtained in good yields and with complete stereoselectivity starting from both α and β azides.
Neighbouring group participation of C-6 substituents of glucose derivatives on the stereoselectivity of the N-glycosidic linkage of glycopeptides
Zhang, Hong,Wang, Yali,Thuermer, Rene,Parvez, Khalid,Choudhary, Iqbal,Atta-Ur-Rahman,Voelter, Wolfgang
, p. 692 - 698 (2007/10/03)
The first example of a glycopeptide with a direct N-α-glycosidic linkage between the trisaccharide and the amino acid residue was found in the glomerular basement membrane of rats. In connection with the total synthesis of nephritogenoside, glycosyl azides with different protecting groups and carbohydrate chain lengths are synthesized, reduced to the corresponding glycosyl amines and coupled with Z-Asp-OBzl. Remarkable differences in the α:β ratio of the condensation products are observed, caused by neighbouring group participation.
Azide and Cyanide Displacements via Hypervalent Silicate Intermediates
Soli, Eric D.,Manoso, Amy S.,Patterson, Michael C.,DeShong, Philip,Favor, David A.,Hirschmann, Ralph,Smith III, Amos B.
, p. 3171 - 3177 (2007/10/03)
Hypervalent azido- and cyanosilicate derivatives, prepared in situ by the reaction of trimethylsilyl azide or trimethylsilyl cyanide, respectively, with tetrabutylammonium fluoride, are effective sources of nucleophilic azide or cyanide. Primary and secondary alkyl halides and sulfonates undergo rapid and efficient azide or cyanide displacement in the absence of phase transfer catalysts with the silicate derivatives. Application of these reagents to the stereoselective synthesis of glycosyl azide derivatives is reported.
