2,3,4-tri-O-acetyl-a-D-glucopyranosyl

Methyl (2,3,4-tri-O-acetyl-a-D-glucopyranosyl iodide)uronate, prepared by the method used for the corresponding D-glucoside derivatives, proved25 to be inadequate for the synthesis of D-gluco-... 

As a first attempt to synthesise uronic acid-containing structures from this polysaccharide and from the polysaccharide of Streptococcus pneumoniae type 3 (Fig. 6) [67], the common Koenigs-Knorr type donor methyl (2,3,4-tri-O-acetyl-a-D-glucopyranosyl bromidejuronate (easily obtained from the 3,6-glucurono-lactone and recrystallised from ethanol [68]) was tried in coupling reactions with the relevant acceptors 44 and 45 (for structures see Scheme 14, p. 189) and... 

Compound 33 also lends itself to the synthesis of 1,5-linked disaccharides. Thus, its condensation180 with 2,3,4,6-tetra-O-acetyl-a-D-glucopyranosyl bromide, and with methyl 2,3,4-tri-O-acetyl-a-D-glucopyranosyluronate bromide, respectively, yields the corresponding /3-D-linked disaccharides (97 and 98). 

T Kinoshita, Y Kasahara, N Nimura. Reversed-phase high-performance liquid chromatographic resolution of non-esterified enantiomeric amino acids by derivatization with 2,3,4,6-tetra-O-acetyl-P-D-glucopyranosyl isothiocyanate and 2,3,4 tri-O-acetyl-a-D-arabinopyranosyl isothiocyanate. J Chromatog 210, 77, 1981. 

Tri-O-acetyl-a-D-glucopyranosyl fluoride, G-262 l-(3,4,6-Tri-0-acetyl-p-i>glucopyranosyI)piperidine, G-435... 

Condensation of the appropriate per-O-acetylated glycopyranosyl bromide with 4-aminobenzenethiol in the presence of sodium methoxide has been used to prepare 4-aminophenyl l-thio-j3-D-gluco-, -galacto-, and -xylo-pyranosides and 4-aminophenyl 2-acetamido-2-deoxy-1 -thio-jS-D-glucopyranoside. 4-Amino-phenyl l-thio-/3-D-glucopyranosiduronic acid was synthesized by condensation of methyl (2,3,4-tri-O-acetyI-a-D-glucopyranosyl bromide)uronate with 4-aminobenzenethiol, followed by saponification with sodium hydroxide. An attempt to obtain the l,2-ci5-l-thioaldopyranoside by reaction of 4,6-di-0-acetyl-2,3-0-carbonyl-a-D-mannopyranosyl bromide (191) with sodium 4-nitrobenzene-... 

Glycosyl fluorides have also been prepared by treatment of per-O-acyl or partially 0-acylated sugars with hydrogen fluoride [liquid HF (for example, see Refs. 38 and 39) or HF in acetic acid or dichloromethane], as exemplified by 2,3,4-tri-O-benzyl-a-D-xylopyranosyl (18), a-D-glucopyranosyl (19), tetra-O-pivaloyl-a-D-glucopyranosyl (20), and 2,3,5-tri-O-acetyl-D-xylofur-anosyl fluorides (21) (see Table 1). Frequently, HF treatment - leads to... 

Consequently, tubuloside D (21) was determined to be 2-(3,4-dihydroxyphenyl) ethyl 2 3,4-tri-O-acetyl-a-L-rhamnopyranosyl (1—3)-0- /W>glucopyranosyl(l— 6)]-(4-0-p-coumaroyl)-2-0-acetyl-/ -D-glucopyranoside. 

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