Neuraminic acid derivatives acids

Figure 10.7 Neuraminic acid derivatives accessible by NeuA catalysis, including an intermediate for alkaloid synthesis.

C-6,209,214 anhydro sugars,branched monosaccharides, fluori-nated amino sugars,difluorinated monosaccharides, and fluorinated monosaccharide phosphates,and phosphonates have been described. Further progress has been achieved in the synthesis and n.m.r.-spectral analysis of fluorinated avermectin Bu, tylono-lide, and neuraminic acid derivatives. " ... 

A synthetic neuraminic acid derivative having a methyl ether group at 0-4 (Neu5Ac4Me) was synthesized by Beau and coworkers101,102 by using an oxymercuration-demercuration reaction.103 The metabolic behavior of this compound will be described in Sections V and VI. 

M.-J. Kim, W. J. Hennen, H. M. Sweers, and C.-H. Wong, Enzymes in carbohydrate synthesis 79-Acetylneuraminic acid aldolase catalyzed reactions and preparation of 7V-aceiyl-2-deoxy-D-neuraminic acid derivatives, J. Am. Chem. Soc. 770 6481 (1988). 

The use of chiral 1-oxa-l,3-butadienes for the stereoselective preparation of carbohydrates has also been investigated by Schmidt et al. [479]. The elegant syntheses of N-acetyl-/J-D-neuraminic acid derivatives are an impressive result of these studies [480]. 

C. Syntheses of Neuraminic Acid Derived Amino Acids... 

Scheme 27. Synthesis of a N-acetyl neuraminic acid derivative...

Hydrolysis of Sialic Acid (Neuraminic Acid) Derivatives... 

The oceurrence of this neuraminic acid derivative (Table 1) has first been described in cerumen of men [37], although its origin in this material remained unknown. Some hints to the possible enzymatic formation (by microorganisms ) come from the discovery... 

In an extension of the previous work [91] Takahashi and co-workers utilized the above procedure for the preparation of KDN and Neu5Ac [92]. In both these syntheses a sugar derived heptosyl bromide 84 was taken as a substrate (Scheme 21). It was reacted with cyanoacetate leading to Z-olefm 85. Stereo- and regioselective functionalization of the double bond in alcohol 85 via oxirane intermediate, and the introduction of acetamido group through trichloroacetimidate furnished 87, transformed into neuraminic acid derivative according to the previously described procedure. 

Influenza virus a- and j8-Ketosides of neuraminic acid derivatives Sepharose 4B 208... 

A careful investigation has been performed on the m.s. of per(tri-methylsilyl) ated neuraminic acid derivatives. " The study demonstrated that m.s. can be a valuable tool for the characterization of these compounds. 

When the neuraminic acid derivative 52 was treated with diethylamine, selective S-deacetylation occurred, and the deacetylated material could be alkylated with various 6-bramo-6-deoxyhexose derivatives to give thioglycoside disaccharides.5i... 

Figure 3.251 Separation of neuraminic acids derived from glycoproteins. Separator column CarboPac PA10 eluent (A) 0.1 mol/L NaOH, (B) 0.1 mol/L NaOH+ 1 mol/L NaOAc gradient linear, 7% B to 30% B in 10 min flow rate ...

Fig. 3-192. Separation of neuraminic acids derived from glycoproteins. - Separator column CarboPac PAIO eluant ...

Neuraminic acid derivatives newly discovered in humans A/-acetyl-9-0-lactoylneuraminic acid, N,9-0-diacetylneuraminic acid and A/-acetyl-2,3-dehydro-2-deoxyneuraminic acid. Hoppe-Seylers Zeitschrift Fur Physiologische Chemie, 357, 1699-1705. 

Neuraminic acid derivatives variously N-acylated have been prepared by reduction-acylation of a 5-azido compound, itself produced from 2-azido-2-deoxy-D-mannose using NeuNAc pyruvate lyase.54... 

Neuraminic Acid Derivatives as MAG Antagonists - First Generation. 172... 

In order to explore further the substmctural determinants of sialic acid required for MAG binding, Kelm and Brossmer [28, 72], and later our group [73, 74], evaluated the inhibitory potential of simple neuraminic acid derivatives towards MAG and... 

As shown above, a broad optimization effort for the 9-position had led to the identification of p-chlorobenzamide as the best substituent ( 147, entry 63 in Table 7). Because the sheer enlargement of the hydrophobic group in the 2-position did not exhibit improved affinities (entries 6-12 in Table 7), the electron densities of the aromatic aglycones were altered in a next step (entries 4-9, Table 8) [81]. Then, with the substituents in the 2- and 9-positions set, a further optimization of the acyl group in the 5-position was conducted (entries 10-16). The binding properties of the neuraminic acid derivatives 155-167 again were evaluated with the hapten binding assay relative to sialoside 147. In addition, the dissociation constants Kjj were determined in a surface plasmon resmiance (SPR) based biosensor (Biacore) experiment [70]. 

Table 8 Relative inhibitory potencies (rIP) and dissociation constants (ATd) of neuraminic acid derivatives as MAG antagonists - second generation. The rlP of each substance was calculated by dividing the IC50 of the reference compound 147 by the IC50 of the compound of interest. This results in rIPs above 1.00 for derivatives binding better than 147 and rIPs below 1.00 for compounds with a lower affinity, n.d . not determined n.b.. not binding...

Neuraminic acid derivatives accessible by NeuA catalysis. 

The procedure consists of stepwise enzymatic degradation of chemically prepared neuraminic acid derivatives (3) to give the corresponding modified ManNAc analogs (1), which is followed by subsequent neuraminic acid reconstruction in the presence of [3- C] labeled pyruvate (21). To ensure complete conversion in the desired direction the first step was promoted by cofactor-dependent reduction of pyruvate the second, synthetic step, was uncoupled by destruction of the nucleotide cofactor before addition of labeled pyruvate. Sialic acids such as 20 with high label incorporation (> 87%) were obtained in good yields (46-76%). 

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