Stereoselective Anhydride Openings

Atodiresei, Iuliana; Schiffers, Ingo; Bolm, Carsten

doi:10.1021/cr068369f

Cited by 186 publications

(78 citation statements)

References 199 publications

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“…Like 4, 6 is a known compound. [34] Both 6 and 4 share tetrahydrophtalic anhydride 9 as the common precursor via the intermediates shown in Scheme 1. Activation of acid 6 as a pyridyl thioester was achieved under Mukaiyama conditions [35] to afford 10 in 67 % yield (Scheme 2).…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Novel DC‐SIGN Ligands with an α‐Fucosylamide Anchor

et al. 2008

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The dendritic cell-specific intercellular adhesion molecule (ICAM) 3-grabbing nonintegrin (DC-SIGN) is a C-type lectin that appears to perform several different functions. Besides mediating adhesion between dendritic cells and T lymphocytes, DC-SIGN recognizes several pathogens some of which, including HIV, appear to exploit it to invade host organisms. The intriguing diversity of the roles attributed to DC-SIGN and their therapeutic implications have stimulated the search for new ligands that could be used as biological probes and possibly as lead compounds for drug development. The natural ligands of DC-SIGN consist of mannose oligosaccharides or fucose-containing Lewis-type determinants. Using the known 3D structure of the Lewis-x trisaccharide, we have identified some monovalent alpha-fucosylamides that bind to DC-SIGN with inhibitory constants 0.4-0.5 mM, as determined by SPR, and have characterized their interaction with the protein by STD NMR spectroscopy. This work establishes for the first time alpha-fucosylamides as functional mimics of chemically and enzymatically unstable alpha-fucosides and describes interesting candidates for the preparation of multivalent systems able to block the receptor DC-SIGN with high affinity and with potential biomedical applications.

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Section: Resultsmentioning

confidence: 99%

Synthesis of Novel DC‐SIGN Ligands with an α‐Fucosylamide Anchor

et al. 2008

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“…This fact was clearly indicative of a chiral recognition phenomenon, probably related to the ability of the Cinchona alkaloid derivatives to act as NMR chiral solvating agents toward suitable chiral substances. [41][42][43][44][45][46][54][55][56] Control experiments with rac-16 (50 mM) and either 4 or 13 (5 mM) in toluene-d 8 , confirmed this hypothesis, showing that even such a small concentration of the alkaloid derivatives was sufficient for inducing a rather large anisochrony in most of the protons of the enantiomers of 16 (e.g., Dd 5 0.011 ppm for the methoxy groups of rac-16 in the presence of 13, Fig. 8a).…”

Section: Reaction Monitoring and Organocatalyst-product Interactionmentioning

confidence: 67%

“…In general, no significant interaction between the alkaloid derivatives (5 mM) and the anhydride substrate (5-50 mM) could be evidenced by these experiments, as deduced from the lack of relevant intermolecular dipolar interaction in the ROESY spectra and the observation of a diffusion coefficient for 15 in the mixtures that proved identical to that of the pure compound in toluene-d 8 ). Furthermore, any significant complexationinduced shift was not detected in the mixtures with respect to the pure anhydride.…”

Section: Organocatalyst-reactants Interactionmentioning

confidence: 83%

“…Several protons resonances were shifted in the NMR spectra and, in the case of 13, the presence of a large excess of MeOH-d 4 led also to the enhancement of the dipolar interaction between the protons H 9 and H 8 , as demonstrated by the much stronger ROE between them (Fig. 7) in comparison with the sample in pure toluene-d 8 (Fig. 4).…”

Section: Organocatalyst-reactants Interactionmentioning

confidence: 93%

“…1,2 Amongst the many processes based on this concept, the alcoholysis of meso-anhydride (Scheme 1) appears remarkably convenient in terms of experimental simplicity, substrate scope, and synthetic versatility of the resulting hemiester products. [3][4][5][6][7][8] In this context, the use of Cinchona alkaloids and their derivatives ( Fig. 1) 9,10 has played a major role since the pioneering studies by Oda and Aitken's groups in the mid 80's.…”

Section: Introductionmentioning

confidence: 99%

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Mono‐ and bis‐quinidine organocatalysts in the asymmetric methanolysis of cis‐1,2,3,6‐tetrahydrophthalic anhydride: A conformational and mechanistic NMR study

Balzano¹,

Jumde²,

Mandoli³

et al. 2011

Chirality

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The enantioselective organocatalytic methanolysis of cis-1,2,3,6-tetrahydrophthalic anhydride mediated by quinidine derivatives with pyridazine or anthraquinone core was investigated, carrying out a detailed nuclear magnetic resonance study of the conformational preferences of the alkaloid catalysts in the pure solvent and in the presence of the reaction substrates and products. No significant interaction between the meso-anhydride and the alkaloid derivatives was detected. In contrast, evidence for a considerable influence of the alcohol reactant on the conformational state of some of the chiral organocatalysts could be obtained, which lends support to the hypothesis of general-base catalysis mechanism, as opposed to the nuclephilic one. The catalytic properties of the studied derivatives showed no obvious correlation with their conformational prevalence in the resting state, suggesting that the alkaloid 9-O substituent should have a more active role than merely enforcing the chiral fragments to adopt a preferential reactive conformation. A strong enantioselective interaction between the enantiomers of the hemiester product and the alkaloid derivatives was also observed, leading to the conclusion that in the actual reaction conditions a relatively large fraction of the latter is in the protonated form.

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Metathesis‐Based Synthesis of Complex Bioactives

Richard

Chen

2012

Modern Tools for the Synthesis of Complex Bioactive Molecules

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Stereoselective Anhydride Openings

Cited by 186 publications

References 199 publications

Synthesis of Novel DC‐SIGN Ligands with an α‐Fucosylamide Anchor

Synthesis of Novel DC‐SIGN Ligands with an α‐Fucosylamide Anchor

Mono‐ and bis‐quinidine organocatalysts in the asymmetric methanolysis of cis‐1,2,3,6‐tetrahydrophthalic anhydride: A conformational and mechanistic NMR study

Metathesis‐Based Synthesis of Complex Bioactives

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