P-D-Galactopyranosides derivatives

The solid-phase synthesis of 1,6-anhydro sugar derivatives, starting with the 2-0-p-toluenesulfonyl-P-D-galactopyranoside derivative 34 (Scheme 14.13), was reported by a... 

N.B. Mahkoside A is the 2-p-D-galactopyranoside derivative of the title compound. It is isolated from Mahkota Dewa (Phaleria macrocarpa [Scheff.] Boerl) [1748],... 

Licania pittieri Prance is a tree up to 15 meters high growing in the cloud forests at 1800 m in altitude. From the methanol extract of the leaves, collected in the Parque Nacional Henry Pittieri, oleanolic acid (1), ursolic acid (2), catechin (3), epicatechin (4), quercetin (5), and four glycosidic derivatives, quercetin 3-O-P-D-galactopyranoside (6), quercetin 3-O-P-D-glucopyranoside (7), quercetin 3-O-a-L-rhamnopyranoside (8), and quercetin 3-O-a-L-arabinopyranoside (9) were identified directly by comparing their spectroscopic data with those reported in the literature and/or authentic samples [see Fig. (1)] [5]. 

In order to try to overcome some of the problems associated with chemical synthesis of oligosaccharides containing N-acetylneuraminic acid, Sabesan and Paulson [277] have used a combination of chemical and enzymatic methods using purified sialyl-transferases in the presence of CMP-iV-acetylneuraminic acid and synthetic acceptor molecules to give sialyl derivatives of oligosaccharides which were characterised by NMR. Thus, methyl P-D-galactopyranoside, methyl P-D-lactoside and iV-acetyl-... 

Regioselective benzylation at the primary position of the 4,6-diol has been observed in a- (Ref. [107]) and P-D-galacto [108, 109] series (see also, Ref. [110]). Benzyl 2,3,6-tri-O-benzyl-P-D-galactopyranoside was obtained crystalline first by this method in 81 % yield [108]. The preference is lower for D-gluco series [45, 105], benzyl 2-acet-amido-3-0-benzyl-2-deoxy-P-D-glucopyranoside gave [45] the desired 3,6-di-O-ben-zyl isomer in only 43% yield, together with 31.5% of 4,6- and 14.8% of 3,4,6-tri-O-benzyl derivative. 

Noleto, G.R., C.A. Tischer, P.A.J. Gorin, M. Iacomini, and M.B.M. Oliveira. 2003. Complexes of sodium vanadatc(V) with methyl a-D-mannopyranoside, methy a- and P-D-galactopyranoside, and selected O-methylated derivatives A 51V and 13C NMR study. Carbohydrate Research 338 1745-1750. 

In like fashion, by careful stereochemical correlation of the three masked hydroxy stereocentres in 4 [i.e. C(13), C(14) and C(15) using FK506 numbering] with various monosaccharide derivatives (Scheme 17.3), Danishefsky was able to establish an appropriate chirality match with the C(2), C(3) and C(4) stereocentres of D-galactose. Methyl p-D-galactopyranoside was therefore selected as the starting material for his synthesis of 4. 

First, ethyl 2-deoxy-2-phthalimido-l-thio-(3-D-glucopyranoside 33 and 40 and phenyl l-thio-p-o-galactopyranoside derivatives 37 and 43 were arbitrarily chosen as disarmed-active donors to be used in the glycosylation reactions with latent-acceptor 17. NIS-TfOH mediated glycosidation of donors 33,40,37, and 43 with 17 afforded the corresponding disaccharides 41, 42, 44, 45 in high yields (78%-89%) with complete p-stereocontrol (Table 2). 

During a study of the substrate specificity of a fucosyltransferase, octyl 3-, 4-, and 6-deoxyfluoro-P-D-galactopyranosides were prepared, while methyl 2-O-a-L-rhamnopyranosyl-a-D-galactopyranoside derivatives selectively fluorinated at the 3-, 4-, or 6- positions of the galactose moiety have been prepared as analogues of the antigenic determinant of the polysaccharide of Shigella dysenteriae ... 

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