188435-38-3Relevant academic research and scientific papers
Stereocontrolled α-Galactosylation under Cooperative Catalysis
Shadrick, Melanie,Singh, Yashapal,Demchenko, Alexei V.
, p. 15936 - 15944 (2020/11/20)
A recent discovery of a cooperative catalysis comprising a silver salt and an acid led to a dramatic improvement in the way glycosyl halides are glycosidated. Excellent yields have been achieved, but the stereoselectivity achieved with 2-O-benzylated donors was poor. Reported herein is our first attempt to refine the stereoselectivity of the cooperatively catalyzed galactosylation reaction. Careful optimization of the reaction conditions along with studying effects of the remote protecting groups led to excellent stereocontrol of α-galactosylation of a variety of glycosyl acceptors with differentially protected galactosyl donors.
Synthesis of 12- O-Mono- and Diglycosyl-oxystearates, a New Class of Agonists for the C-type Lectin Receptor Mincle
Van Huy, Le,Tanaka, Chiaki,Imai, Takashi,Yamasaki, Sho,Miyamoto, Tomofumi
, p. 44 - 49 (2019/01/15)
Fifteen glycosyl-oxystearates were synthesized by Crich's 4,6-benzylidene and K?ening-Knorr strategies. Assessment of structure-activity relationships using macrophage-inducible C-type lectin (Mincle) receptor cells expressing nuclear factor of activated
ENDOSOMAL CLEAVABLE LINKERS
-
, (2018/08/20)
The present disclosure relates generally to cleavable linkers and uses thereof.
OFox imidates as versatile glycosyl donors for chemical glycosylation
Nigudkar, Swati S.,Wang, Tinghua,Pistorio, Salvatore G.,Yasomanee, Jagodige P.,Stine, Keith J.,Demchenko, Alexei V.
, p. 348 - 359 (2017/01/13)
Previously we communicated 3,3-difluoroxindole (HOFox)-mediated glycosylations wherein 3,3-difluoro-3H-indol-2-yl (OFox) imidates were found to be key intermediates. Both the in situ synthesis from the corresponding glycosyl bromides and activation of the
Regenerative glycosylation under nucleophilic catalysis
Nigudkar, Swati S.,Stine, Keith J.,Demchenko, Alexei V.
supporting information, p. 921 - 923 (2014/02/14)
This article describes 3,3-difluoroxindole (HOFox)-mediated glycosylation. The uniqueness of this approach is that both the in situ synthesis of 3,3-difluoro-3H-indol-2-yl (OFox) glycosyl donors and activation thereof can be conducted in a regenerative fashion as is a typical reaction performed under nucleophilic catalysis. Only a catalytic amount of the OFox imidate donor and a Lewis acid activator are present in the reaction medium. The OFox imidate donor is constantly regenerated upon its consumption until glycosyl acceptor has reacted.
Synthesis of a chlorogenin glycoside library using an orthogonal protecting group strategy
Wang, Ying-Hsin,Yeh, Hsien-Wei,Wang, Hsiao-Wen,Yu, Chia-Chun,Guh, Jih-Hwa,Liu, Der-Zen,Liang, Pi-Hui
, p. 118 - 135 (2013/07/27)
Naturally occurring spirostanol saponins bear a chacotriose, α-l-rhamnopyranosyl-(1→2)-[α-l-rhamnopyranosyl-(1→4)] -β-d-glucopyranose residue as the oligosaccharide moiety which is believed to be important for biological activity. Herein the development of a concise, combinatorial method for the synthesis of two series of glycan variants at the 2′ and/or 4′ positions of chacotriose is described and the structure-activity relationships of the glycone part at 3-OH of chlorogenin investigated. These compounds were found to be weakly-cytotoxic toward leukemia cell lines CCRF and HL-20, indicating that the chacotriose moiety is important for anticancer activity.
SnCl4- and TiCl4-catalyzed anomerization of acylated O - And S -glycosides: Analysis of factors that lead to higher α: β d reaction rates
Pilgrim, Wayne,Murphy, Paul V.
supporting information; experimental part, p. 6747 - 6755 (2010/12/25)
The quantification of factors that influence both rates and stereoselectivity of anomerization reactions catalyzed by SnCl4 and TiCl4 and how this has informed the synthesis of α-O- and α-S-glycolipids is discussed. The SnCl4-catalyzed anomerization reactions of β-S- and β-O-glycosides of 18 substrates followed first order equilibrium kinetics and kf + kr values were obtained, where kf is the rate constant for the forward reaction (β → α) and kr is the rate constant for the reverse reaction (α → β). Comparison of the kf + k r values showed that reactions of glucuronic acid or galacturonic acid derivatives were ～10 to 3000 times faster than those of related glucoside and galactopyranoside counterparts and α:β ratios were generally also higher. Stereoelectronic effects contributed from galacto-configured compounds were up to 2-fold faster than those of corresponding glucosides. The introduction of groups, including protecting groups, which are increasingly electron releasing generally led to rate enhancements. The anomerization of S-glycosides was consistently faster than that of corresponding O-glycosides. Reactions were generally faster for reactions with TiCl4 than those with SnCl4. Anomeric ratios depended on the Lewis acid, the number equivalents of the Lewis acid, temperature, and substrate. Very high ratios of α-products for both O- and S-glucuronides were observed for reactions promoted by TiCl4; for these substrates TiCl4 was superior to SnCl4. Anomeric ratios from anomerization of S-glucosides were higher with SnCl4 than with TiCl4. The dependence of equilibrium ratio on Lewis acid and the number of equivalents of Lewis acid indicated that the equilibrium ratio is determined by a complex of the saccharide residue bound to the Lewis acid and not the free glycoside. The high α:β ratios observed for anomerization of both O- and S-glycuronic acids can be explained by coordination of the C-1 heteroatom and C-6 carbonyl group of the product to the Lewis acid, which would enhance the anomeric effect by increasing the electron-withdrawing ability of the anomeric substituent and lead to an increase in the proportion of the α-anomer. Such an observation would argue against the existence of a reverse anomeric effect. Support for a chelation-induced endocyclic cleavage mechanism for the anomerization is provided by the trapping of a key intermediate. The data herein will help predict the tendency of β-glycosides to undergo anomerization; this includes cases where 1,2-trans glycosides are initial products of glycosidation reactions catalyzed by TiCl4 or SnCl4.
Synthesis of urea tethered glycosylated amino acids and glycopeptides mediated by DPPA employing Nα-Fmoc-Asp/Glu-5-oxazolidinones
Nagendra,Hemantha,Sureshbabu, Vommina V.
scheme or table, p. 397 - 407 (2009/12/26)
The utility of diphenyl phosphoryi azide (DPPA) as azido transfer reagent for the insertion of urea moiety between β/γ carboxyl group of N a-Fmoc-Asp/Glu-5-oxazolidinones and glycosyl amine has been demonstrated. Utility of this protocol for the synthesis of urea-linked neoglycopeptides has also been explored. The compounds are characterised by '1H NMR, l3C NMR and mass spectroscopy.
