Regio- and stereoselective synthesis of 3- and 5-(C-glycosyl)-4-nitroisoxazolidines by nitrone–nitroalkene [3+2] cycloaddition reactions

Borrachero, Pastora; Cabrera, Francisca de la Maza; Diánez, M. J.; Estrada, M. D.; Gómez-Guillén, Manuel; López-Castro, A.; Moreno, J.M. Caldero ́n; Paz, José L. de; Pérez-Garrido, Simeón

doi:10.1016/s0957-4166(98)00488-1

Cited by 15 publications

(2 citation statements)

References 22 publications

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“…The endo/exo stereoselectivity was found to be dependent on the type of sugar derivatives used and worse selectivity was observed when noncarbohydrate derived nitrones or nitroolefins were employed (Scheme 60, Table 4). 91 In general, it was observed that the exo/endo and/or the π-facial stereoselectivities were better for reactions of C-glycosyl nitrones than for those of sugar nitroalkenes (Fig. 8).…”

Section: Intermolecular Reactions Between Carbohydrate Derived Nitron...mentioning

confidence: 90%

1,3-Dipolar cycloaddition reactions of carbohydrate derived nitrones and oximes

Osborn

Gemmell

Harwood

2002

J. Chem. Soc., Perkin Trans. 1

121

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Section: Intermolecular Reactions Between Carbohydrate Derived Nitron...mentioning

confidence: 90%

1,3-Dipolar cycloaddition reactions of carbohydrate derived nitrones and oximes

Osborn

Gemmell

Harwood

2002

J. Chem. Soc., Perkin Trans. 1

121

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“…However, starting from the di-O-acetylated dimethyl acetal 12, the nitrone 22 was obtained (entry 10) in good yield (67%), thus opening potential access to longchain functionalized C-disaccharides through isoxazolidine derivatives. 15 For instance, the 1,3-dipolar cycloaddition reaction of 22 with the D-galactose derived nitroolefin 23 led to the 3,5-di-C-glycosyl-4-nitroisoxazoScheme 2 Synthetic routes to C-glycofuranoside-based building blocks (C-GfBB, types 2-5) via formyl C-glycofuranosides (see Table 1 . 16 The configuration assignment was made on the basis of the stereospecificity of the cycloaddition reactions, and the exo/endo and facial stereoselectivities observed for related reactions.…”

Section: Methodsmentioning

confidence: 99%

Easy Access to Configurationally Controlled C-Glycofuranoside-Based Building Blocks by Means of Formyl C-Glycofuranosides

Vera-Ayoso¹,

Borrachero²,

Cabrera‐Escribano³

et al. 2009

Synlett

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A general approach to enantiopure C-glycofuranosidebased hybrid a/b-amino acids and nitrones, among other valuable building blocks, has been established via formyl C-glycofuranosides, easily available from hexose-derived equatorial-2-OH-glycopyranosides by DAST-promoted ring contraction.The replacement of the exocyclic carbon-oxygen or carbon-nitrogen bond of native glycoconjugates with a carbon-carbon bond creates compounds which are resistant to chemical and enzymatic degradation with minimal loss or enhancement in biological activity with respect to the parent O-or N-glycosides. 1 Therefore the ready access to C-glycosides is of great interest in carbohydrate chemistry. 2 A major problem to prepare functionalized C-glycosides relies on the few available anomeric carbon-carbon bondforming reactions endowed with both chemical efficiency and stereocontrol. This problem could be avoided by the use of C-functionalized carbohydrate derivatives bearing an a-or b-linked highly reactive carbon functionality at the anomeric center. Following this idea, we have developed by means of formyl C-glycofuranosides 1, a widescope method for the synthesis of configurationally controlled C-glycofuranoside-based building blocks containing the substructures 2-4 (Scheme 1), from which an easy access to biologically relevant more complex C-glycofuranoside-based molecules (C-oligosaccharides and Cglycoconjugates) is provided. The key step in this strategy is clearly a DAST-mediated rearrangement reaction that involves ring contraction of hexose-derived equatorial 2-OH-glycopyranosides, and leads to formyl C-glycofuranosides under remarkably mild conditions. This methodology allowed us to prepare a series of formyl Cglycofuranosides, 3 and from the point of view of atom economy 4 it can be considered in the carbohydrate field as a greener formylation methodology than those strategies that are based on the use of formyl anion equivalents. 5 We have employed formyl C-glycofuranosides 1 as key intermediates via reductive amination of the formyl group for the synthesis of enantiopure N-substituted 1-C-aminomethyl glycofuranosides 5 (Figure 1). 6

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1,3‐Dipolar Cycloaddition

2010

Comprehensive Organic Name Reactions and Reagents

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Regio- and stereoselective synthesis of 3- and 5-(C-glycosyl)-4-nitroisoxazolidines by nitrone–nitroalkene [3+2] cycloaddition reactions

Cited by 15 publications

References 22 publications

1,3-Dipolar cycloaddition reactions of carbohydrate derived nitrones and oximes

1,3-Dipolar cycloaddition reactions of carbohydrate derived nitrones and oximes

Easy Access to Configurationally Controlled C-Glycofuranoside-Based Building Blocks by Means of Formyl C-Glycofuranosides

1,3‐Dipolar Cycloaddition

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