Trisaccharides derivatives

The first synthesis, by method a, of amylostatin (XG) was reported by Kuzuhara and Sakairi. The synthon for the cyclohexene moiety was the benzylated allyl bromide 382, derived from D-glucose by the sequence 378 — 382 of the Perrier reaction. The coupling reaction of 382 using an excess of 4-amino-T,6 -anhydro-4,6-dideoxymaltose tetrabenzyl ether (383), and sodium iodide in DMF for 3 days produced a mixture of the epimeric monocarba-trisaccharide derivatives, separation of which gave the protected derivatives in 15% yield. 

Similarly Thiem and Wiemann (92) conducted the galactosylation of the 2-acetamido-2-deoxy-D-glucose-L-asparagine derivative 183 and the chitobiose-L-asparagine derivative 187 to furnish the di- and trisaccharide derivatives 185 and 188, respectively, by using galactosyltransferase. 

We now turned our attention to the second approach, the alkylation of a cyclohexenyl amine by some trisaccharide derivative. The logical choice of amine was the 1-epivalienamine derivative 81, a molecule that was readily available through various literature procedures. We chose to utilize the excellent synthesis described by Panza et al. to produce multi-gram amounts of the amine 81 [56]. 

Scheme 7 Synthesis of Le trisaccharide derivative via TOPCAT-mediated glycosylation.

The situation that exists in the case of the biosynthesis of neutral polysaccharide chains of streptococcal cell-wall is still very uncertain. In S. sanguis, assembly of the trisaccharide derivative (45, X = an unidentified, hydro-phobic group) from UDP-GlcNAc, dTDP-Rha, and UDP-Glc on an... 

For this purpose, the synthetic trisaccharide derivative II was converted, through the decaacetate III, into the acetohalogenose IV which, by treatment with KCN in CH CN was transformed into the 1,2-cyano-ethylidene derxvative XII (18). Compound XII, by very mild treatment with dilute CH ONa, was converted into... 

In the synthesis of the glycolipid asialo GMI described by Ogawa and co-workers [107] the trisaccharide derivative (215) (used in the synthesis of asialo GM2) was converted into the 4,6-O-benzylidene derivative (233) and this was condensed with aceto-bromogalactose in the presence of mercury(II) cyanide and molecular sieves to give the P-linked acetylated galactose derivative in 97 % yield. The product was deprotected and acetylated to give the peracetyl derivative (234) of the tetrasaccharide which was converted into the free sugar (235) with hydrazine hydrate. Compound (235) was converted into asialo GMI via the imidate as described above for the synthesis of asialo GM2 from the imidate (219). 

Kitajima et al. [264] used the mixture of mercury salts and molecular sieves in 1,2-dichloromethane to condense (370) with the trisaccharide derivative (382) to give similar tetrasaccharides [on the primary hydroxyl group of (382)] with again equal amounts (30% each) of a- and (3-linked derivatives. With the allyl glycoside (383) under the same conditions 48 % of a- and 33 % of P-linked glycosides were obtained [265]. The a-isomer was used to prepare [265] the undecasaccharide characteristic of the complex type of glycan of glycoproteins. 

Conversion of the 1,2-trans to the 1,2-cis configuration by oxidation and reduction of the C-2 in the paratoside trisaccharide derivative, according to Scheme 42, followed by deprotection reactions, afforded the corresponding tyveloside 140.222... 

P. Y. Goueth, G. Ronco, and P. Villa, Synthesis of ether-linked di- and trisaccharide derivatives. 1. Synthesis of disaccharides from 5,6-anhydro-D-glucose derivatives, J. Carbohydr. Chem., 13 (1994) 679-696. 

Zeng XX, Murata T, Usui T. Glycosidase-catalyzed synthesis of fucosyl di- and trisaccharide derivatives using alpha-L-fucosidase from Alcaligenes sp. J. Carbohydr. Chem. 2003 22 309-316. 

Following the enzymatic synthesis of CMP-Neu5Ac, isolated a2-6-sialyl-transferases could be used to introduce sialic acid to the N-acetyl lactosamine derivates a-f in position 6. This afforded a series of trisaccharide derivates Neu5Aca2-6 Gal l-4GlcNAc l-R. The unblocked trisaccharide a [55], the methyl glycoside b [56], the -Asn derivative c [57], the pentapeptide derivative d [58], the allyl e [59], and the pent-4-enyl glycoside f [48] can be prepared in convincing yields (Fig. 6). 

Conformationally constrained trisaccharide derivatives synthesized and studied by Bundie and coworkers... 

T. Hiroshi, N. Matoba, and T. Takahashi, Effective one-pot synthesis of H type 1 and 2 trisaccharide derivatives using glycal epoxide, Chem. Lett., 34 (2005) 400-401. 

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