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Disialic acid

Synthesis of an Oligomer of Sialic Acid 5.1 [Pg.1343]

The synthesis of a-(2-8)-hnked disialic acid is complicated because of the remarkably diminished reactivity of the C8 hydroxyl of Neu5Ac. The difficulty was exemphfied by the unsuccessful results of the reaction shown in O Scheme 37 [38]. Schmidt has hypothesized that the... [Pg.1343]

The first accomplishment of a-(2-8)-disialic acid synthesis came with the combined use of the 3-hydroxy derivative of NeuSAc 21 and 2,3-en derivative of NeuSAc 137, which was expected to prevent the intramolecular hydrogen bonding between the C8 hydroxyl and Cl-carboxylate group or C2-OR bond. The coupling reaction was promoted by AgOTf in the presence of NaHP04 to afford the dimer 138 in 34% yield as a 3/1 mixture of aip anomers (O Scheme 38) [110]. [Pg.1344]

Similar to the reactivity tuning of sialyl donors mentioned above, it was found that the modification of the C5 acetamido group or its substitution by other functionalities also raises the reactivity of the C8 hydroxyl of sialic acid. Boons and co-workers originally synthesized iV,iV-diacetyl sialyl acceptor 144, which was applied to the sialylation with lV,lV-diacetyl sialyl donor 93 in MeCN at —40 °C. In comparison to iV-acetyl sialyl acceptor 145, the sialylation produced Q -(2-8)-disialic acid 146 in raised yield (50%, aip = 2/1) (O Scheme 40) [94,95]. [Pg.1345]

Despite the development of the exquisite methods for a-(2-8)-linked disialic acid synthesis discussed above, the assembly of the a-(2-8)-linked oligomer has been far from a success. Recently, Tanaka disclosed the unpredictable difficulty of the oligomer synthesis. As mentioned above, the coupling of A-Troc-protected sialic acid donor and acceptor successfully delivered the dimer of sialic acid. However, the A-Troc donor 163 was hardly incorporated into the A-Troc disialyl acceptor 164 the glycosylation produced the stereo mixture of trisial-ic acid 165 in 6% yield (O Scheme 45) [114]. [Pg.1347]

Recently, various new gangliosides have been isolated from marine animals, some of which have a a-(2-4)-linked disialic acid residue within their glycan structures [120,121], The con-stmction of the a-(2-4)-linkage is not straightforward, due to the low reactivity of the C4 hydroxyl of NeuSAc. [Pg.1349]

An initial attempt of sialylation of the C4 hydroxyl of the NeuSAc derivative 181 with iV-Troc sialyl donor 104 in our laboratory resulted in the production of a stereo mixture of disialic acid 182 in less than 10% yield (O Scheme 48) [115],... [Pg.1349]

Keywords Chemical analysis Deaminoneuraminic acid Disialic acid DMB derivatization Immunochemical analysis Immunohistochemistry A-Glycolylneuraminic acid 0-Acetylated sialic acid Oligosialic acid 0-Sulfated sialic acid Polysialic acid... [Pg.75]

Sato C, Matsuda T, Kitajima K (2002) Neuronal differentiation-dependent expression of the disialic acid epitope on CD 166 and its involvemtait in neurite formation in Neuio2A cells. J Biol Chem 277 45299 5305... [Pg.100]

Yasukawa Z, Sato C, Kitajima K (2007) Identification of an inflammation-inducible serum protein recognized by anti-disialic acid antibodies as carbonic anhydrase II. J Biochem 141 429-441... [Pg.102]


See other pages where Disialic acid is mentioned: [Pg.363]    [Pg.319]    [Pg.492]    [Pg.1313]    [Pg.1313]    [Pg.1339]    [Pg.1339]    [Pg.1344]    [Pg.1347]    [Pg.1349]    [Pg.100]    [Pg.313]    [Pg.314]    [Pg.23]   
See also in sourсe #XX -- [ Pg.75 , Pg.79 , Pg.82 ]

See also in sourсe #XX -- [ Pg.314 , Pg.315 , Pg.326 ]




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