The synthesis of O-glucuronides

Stachulski, Andrew V.; Jenkins, Gareth V.

doi:10.1039/a815173y

Cited by 113 publications

(80 citation statements)

References 125 publications

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“…Final lactonic products 7Á10 were characterized by a typical 1 H NMR chemical shift around d 5.04 ppm, associated to a lowfield resonance for the anomeric carbon at d 109 ppm, clearly confirming the formation of the b-adduct. Incorporation of the vinyl fragment onto the sugar structure was also corroborated by 13 The feasibility of our microwave-assisted procedure was also underlined for the functionalization of DGlcA with other representative alcohols: chloropropanol, benzyl alcohol, phenol, 1,6-hexanediol, and propargyl alcohol. In most cases, syntheses were conveniently achieved, providing in good yields the corresponding b-adducts 11Á15 as the dominant forms.…”

Section: Microwave-assisted Reaction Between D-glca and Various Nuclementioning

confidence: 74%

“…In this case, yields reached up to 85% and contrasted with previous work, involving extended reaction times and recourse to vacuum techniques (37). Unequivocal evidence of the predominant formation of a,b-furanosidic forms was supported by 13 C NMR analyses (in combination with homonuclear and heteronuclear correlation experiments) with signals for C-4 around 83Á85 ppm, more deshielded than in a,b-pyranuronate compounds (d C-4 typically close to 69Á71 ppm) (38,39). were purchased from commercial suppliers and used as received.…”

Section: Extension Of the Microwave-assisted Protocol To D-galacturonmentioning

confidence: 85%

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Efficient microwave-promoted synthesis of glucuronic and galacturonic acid derivatives using sulfuric acid impregnated on silica

Richel

Nicks

Praly

et al. 2012

Green Chemistry Letters and Reviews

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Monomode microwave-assisted syntheses of D-glucuronic and D-galacturonic acid derivatives are reported in the presence of a solid acid catalyst, consisting of sulfuric acid loaded onto silica. This approach affords a variety of surface-active monoglycosylated glucofuranosidurono-6,3-lactones and disubstituted galacturonic adducts in excellent yields in less than 10 min at 858C. This study illustrates the application of microwave heating mode, in combination with a cost-effective solid catalyst, as an efficient, selective, and eco-friendly methodology in carbohydrate chemistry.

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Section: Microwave-assisted Reaction Between D-glca and Various Nuclementioning

confidence: 74%

Section: Extension Of the Microwave-assisted Protocol To D-galacturonmentioning

confidence: 85%

Efficient microwave-promoted synthesis of glucuronic and galacturonic acid derivatives using sulfuric acid impregnated on silica

Richel

Nicks

Praly

et al. 2012

Green Chemistry Letters and Reviews

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“…The β-O-glucosidic linkage is an essential structure in natural products containing sugar chains and glycosides of (11,18). When the use of the acyl group is inconvenient, benzyl-protected glycosyl donors 18 have often been employed using nitriles as reaction solvents or using S N 2-type reactions because the substrate lacks the factor to induce the β-selectivity (Scheme 4).…”

Section: B β-Selective O-glucosylation Reaction Using the Axialrich mentioning

confidence: 99%

O-Glycosylation Reaction Using Axial-rich Glycosyl Donors

Yamada

2011

TIGG

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We d e s c r i b e L -O -r h a m n o s y l a t i o n a n d D -Oglucosylation reactions using glycosyl donors in which the pyranose rings were restricted in a conformation that possessed more axial substituents. We call this conformation the axial-rich form. Introduction of the bulky silyl-protecting groups onto the adjacent trans-diols on the sugars restricted the conformation to the axial-rich form. The axial-rich L-rhamnosyl donor provided the β-isomer preferentially in the glycosylation reaction when trichloroacetimidate was adopted as the leaving group; however, the α/β ratio was only 1/4. This value was insufficient for practical applications. By contrast, the axial-rich glucosyl donor induced a highly β-selective reaction in which the anomeric α/β ratio was up to 2/98. In this case, the axial-rich skew-boat conformation of the pyranose ring was the key to successful stereoselective glycosylation. This method is an alternative for construction of the β-O-glucosidic linkages without relying upon participation of neighboring groups, a method that has long been employed. The new method was particularly effective for the synthesis of 2-O-glycosylated β-O-glucosides, for which direct construction using the neighboring group participation method is difficult. A. O-Rhamnosylation Reaction Using Axial-rich Glycosyl DonorL-rhamnose (1) readily provides α-isomers via an O-glycosylation reaction (Scheme 1)(1). But how can we synthesize the β-isomer? We commenced this study to address this question. The marked preference for the α-isomer originates from the steric and stereoelectronic effects, both of which favorably introduce the α-approach of an alcohol, which is a glycosyl acceptor, to the oxocarbenium ion reaction intermediate. Thus, the axial 2-O-substituent hinders the approach from the β-face, as in 2. Additionally, the α-rhamnosidic linkage orients axially to induce an anomeric effect. Therefore, the entire shape of the rhamnose

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“…The synthetic utility of trichloroacetimidates [5] as glycoside donors has long been realized and has resulted in increased application in both glycoside formation [5] and glucuronidation [6][7][8]. The mild conditions required and the high selectivity for β-glycoside formation make trichloroacetimidates highly attractive choices as the main intermediates for many syntheses.…”

Section: Introductionmentioning

confidence: 99%