2.3.4.6- Tetra-O-acetyl-D-glucopyranosyl

On treatment of trialkylsilyl nitronates 1043 with MeLi, LiBr, or BuLi in THF the resulting nitrile oxide intermediates 1044 afford, in dilute THF solution (R=Me) the ketoximes 1045 in ca 50-60% yield, whereas in concentrated THF solution the O-silylated hydroxamic acids 1046 are obtained as major products [144] (Scheme 7.35). Analogously, the silyl nitronate 1047 reacts with the 2,3,4,6-tetra-O-acetyl-/ -D-glucopyranosyl thiol/triethylamine mixture to afford, via the thiohydroxi-mate 1048, in high yield, a mixture of oximes 1049 which are intermediates in the synthesis of glucosinolate [145] (Scheme 7.35). 

Kobayashi and co-workers (42) reported a general synthetic pathway for the incorporation of oligosaccharides into [60]fullerene via cycloadditions between glycosyl azides and the fullerene (Scheme 9.42). The cycloaddition of 2,3,4,6-tetra-O-acetyl-D-glucopyranosyl azide 197 with [60]fullerene in refluxing chlorobenzene... 

Several catalysts and initiator systems have been tested for the polymerization of GlcAnBzl3, including the following Lewis acids boron trifluoride and its etherate, phosphorus pentafluoride, titanium tetrachloride, and antimony pentachloride and pentafluoride. Several cationic initiators have also been used, including (triphenylmethyl) antimony hexachloride, 2,3,4,6-tetra-O-acetyl-D-glucopyranosyl hexa-fluorophosphate, acetyl hexafluorophosphate, pentamethylbenzyl hexa-fluorophosphate (most of which were generated in situ), and triethyl-... 

It should be emphasized that these factors are not pre-requisites but merely indicate structural features which can be used to identify the more useful reagents e.g. thioureas from catecholamines and 2,3,4,6-tetra-O-acetyl- -D-glucopyranosyl isothiocyanate (GITQ and 2,3,4-tri-O-acetyl-a-D-arabinopyranosyl isothiocyanate (AITC) were separated [12] because of their structural rigidity and hydrophobicity, even though the distance between the chiral centres is greater than three bonds. ... 

Tetra-Ac I-(2,3,4,6-Tetra-O-acetyl-D-glucopyranosyl)piperidine C19H29NO9 415.439 Mp 123°. 

Photolysis of 2,3,4,6-tetra-O-acetyl-l-C-cyano-P-D-galactopyranosyl azide gave the oxazepine derivative 110 in 50% yield a similar product was obtained from the D-arabinopyranosyl analogue. Full details have been reported on the formation of various tetrazole derivatives by photolysis and thermolysis of 1,1-diazido-sugar derivatives (cf. Vol.27, p.l38 Vol.28, p.l54). Compound 111 was the unexpected product from reaction of 2,3,4,6-tetra-O-acetyl-D-glucopyranosyl-idene 1,1-diazide with triphenylphosphine. ... 

Glycosylation of Methyl 3-0-acetyl-4,6-benzylidene-[Pg.227]

Fig. 5 Structures of the selenium-containing carbohydrates 9, bis(2,3,4,6-tetra-0-acetyl-/3-D-glucopyranosyl) selenide 10, bis(2,3,4,6-tetra-0-acetyl-/S-D-galactopyranosyl) selenide 11, bis(2,3,4-tri-0-acetyl-/S-D-arabinopyranosyl) selenide 12, bis(l,2 3,4-di-0-isopropylidene-6-deoxy-/3-D-galactopyranosyl) selenide 13, 4 -methylbenzoyl 2,3,4, 6-tetra-O-acetyl-D-selenoglucopyranoside 14, 4 -methylbenzoyl 2,3,4,6-tetra-0-benzo)d-D-selenoglucopyranoside 15, 4 -methylbenzoyl 2,3,4,6-tetra-0-acetyl- 8-D-selenogalacto-pyranoside 16, 4 -methylbenzoyl 2,3,4,6-tetra-O-acetyl-D-selenomanopyranoside 17, 4 -methylbenzoyl 2,3,4,6-tetra-O-acetyl-D-selenorhamnopyranoside 18, ethyl 2,3,4,6-tetra-0-acetyl-/3-D-selenoglucopyranoside [45]...

Defaye and coworkers52 prepared a-D-glucopyranosyl a-D-xylopy-ranoside (67) and a-D-glucopyranosyl a-D-mannopyranoside in 49 and 44% yields, respectively, by the reaction of the appropriately protected glycopyranosyl bromide (65) with 2,3,4,6-tetra-O-acetyl-D-glu-copyranose (66) in a mixture of benzene and acetonitrile in the presence of mercury(II) bromide and mercury(II) cyanide. 

Treatment of the disaccharide derivative, 2,3,6-tri-0-acetyl-4-0-(2,3,4,6 - tetra- O- acetyl d - galactopyranosyl) -)J-d -glucopyranosyl-... 

Tetra-O -acetyl-p-D-glucopyranosylamine, G-533 l-(2,3,4,6-Tetra-0 -acetyl-D-glucopyranosyl)piperidine, G-435 (2,3,4,6-Tetra-0-acetyl-a-D-glucopyranosyl)(2,3,4,6-tetra-0-acetyl-p-D-... 

Cl7H23NOiOf 1,5-Di-0-acetyl-3-C-(R)-ethoxycarbonylmethyl-5(R),1 (R)-N-formylepimino-2,3-0-isopropylidene- -D-ribofuranose, 42B, 333 Cl7H2 Oio, 1-(2,3,4,6-Tetra-O-acety1- -D-glucopyranosyl)-2,3-(2R)-epoxypropane, 43B, 554... 

The carbohydrate 2,3,4,6-tetra-O-acetyl-a-D-glucopyranosyl bromide reacts with NaCo(CO)4 and PPh3 under 10 atm of CO to yield the expected acetyl (XXIX) and the corresponding alkyl 210). The former decarbonylates readily on storage or chromatography. Retention of configuration at carbon accompanies CO elimination. 

The Helferich-Wedemeyer procedure may give mixtures of the anomers, depending on the nature of the aglycon. For example, condensation of bromide 128 with N-(benzyloxycarbonyl)-L-threonine penta-chlorophenyl ester (171) gave both N-(benzyloxycarbonyl)-3-0-(2,3,4,6-tetra-O-acetyl-a- and -/J-D-glucopyranosyl)-L-threonine pen-tachlorophenyl ester135 (172 and 173, respectively), but only the fi-D... 

The disaccharide derivative 0-(2,3,4,6-tetra-0-acetyl-/ -D-galactopy-ranosyl)-(l— 3)-0-(2-acetamido-6-0-benzoyl-2-deoxy-/ -D-glucopyran-osyl)-(l— 3)-N-(benzyloxycarbonyl)-L-serine methylamide (192) was prepared by condensation of 3-0-(2-acetamido-2-deoxy-6-0-benzoyl-/ -D-glucopyranosyl)-N-(benzyloxycarbonyl)-L-serine methylamide (191) with tetra-O-acetyl-a-D-galactopyranosyl bromide147 (110) under the conditions of the Helferich-Wedemeyer procedure. Treatment of 192 with methylamine in methanol at 0° gave89 193. 

Similarly, treatment of the salt with 2,3,4,6-tetra-O-acetyl-a-D-glucopyra-nosyl bromide 46 gave 4-[2,3,4,6-tetra-0-acetyl-/3-D-glucopyranosyl]-4//-pyrido[2,3-e][l,2,4]triazin-3-one 1-oxide 47. Antileukemia tests for the 4-alkyl derivatives showed no activity. 

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