Glucosylamine N -

Die Halbwertszeiten des Austauschs von N-p-Tolyl-glucosylamin, N-p-Tolyl-4.6-0-benzyliden-glucosylamin,N-p-Tolyl-3.4.5.6-tetrabenzoyl-glucosylamin und Glykolaldehyd-p-toluidid mit p-Toluidin imter-scheiden sich um GroBenordnungen (vgl. Tabelle 1). Nach 1. c. i7) ist der Mechanismus 35 39 - 40 - 41 - -42 - 37 oder 35 39 - -41 - -42 - ... 

For the N-acylaldobiosylamines, this method requires a second oxidation and further reduction, as shown for N-acetyl-6-O-a-D-galactopyranosyl-/3-D-glucosylamine (N-acetyl-/3-meIibiosylamine)49 (54) in the following sequence. 

Nach 1. c. 17) zeigt die RG in Athanol ein pH -abhangiges Maximum, das, ahnlich wie bei der Hydrolyse, fiir N-p-Nitrophenyl-glucosylamin in starker sauerem Bereich liegt als fiir N-p-Tolyl-glucosylamin i ). Es konnte wahrscheinlich gemacht werden, daB die Transglycosidierung spezifisch Saure-katalysiert ist. 

The rate constants kr and k2 have values of 20 X 10-3 and 22 X 10-3 min-1, respectively, in 2 M hydrochloric acid at 100°, and the overall rate of decomposition of 2-acetamido-l-N-/3-L-aspartyl-2-deoxy-/3-D-glucosylamine occurs with a rate constant of 42 X 10-3 min-1, that is, a half-life of the order of 17 minutes.92 L-Aspartic acid and ammonia are released at the same rate.92-95... 

An experiment whose results support certain mechanistic views (see Section VI, p. 110) was the ammonolysis of 2,3,4,6-tetra-O-benzoyl-D-glucopyranosylamine,30 which afforded a mixture of D-glucose and D-glucosylamine in 95% yield, and only 1.4% of l,l-bis(benzamido)-l-deoxy-D-glucitol (17) with traces of N-benzoyl-D-glucopyranosylamine. 

Figure 13. Formation of glucosyl-n-butylamine and glyoxal dialkylimine during the reaction of glucose (0.25 MJ with t-butylamine (1 MJ in ethanol. Key 0, glucosylamine A, imine 9, browning.

Oxidation of N-Acetyl-D-glucosylamine.98 Six grams (0.027 mole) of N-acetyl-D-glucosylamine (XLI) in 100 cc. of water is added to 18.5 g. (0.081 mole) of paraperiodic acid in 100 cc. of water, and the reaction mixture is maintained at 25° for four and one-half hours, which is known from analytical data obtained in small-scale experiments to be sufficient time for completion of the reaction with the consumption of two moles of the oxidant. The solution is exactly neutralized with barium hydroxide, the precipitate removed, and the filtrate evaporated to dryness in vacuum. The solid is extracted with 100 cc. of absolute ethanol, the ethanol extract evaporated to dryness, the residue taken up in ethanol, and the solution is centrifuged and again evaporated to dryness. The product, the dialdehyde XLII, can be converted into the corresponding barium salt (see reference 93). 

N-Acetyl-D-glucosylamine (XLI). Acetamino-D-hydroxymethyl diglycolic aldehyde (XLII) " 93... 

In solution, phase amino acid derived methyl ester N-Fmoc-Tyr-OMe 4 was successfully condensed under Mitsunobu conditions with 2,3,4,6-tetra-Oacetyl-D-glucose 2 to afford the fully protected glucosylamine 5. The reaction provides products of analytical purity and predictable stero-chemistry, as confirmed by H/ C NMR. Synthetic conditions and protective groups for glycopeptides synthesis have been investigated. Mitsunobu conditions employed in solution phase are based on the improved redox system l,l -azodicarbonyldipiperidine (ADDP)—tributylphosphine (TBP) in... 

Under certain conditions, aldosylamines undergo a transglycosylation, in which the amine residue is replaced by another amine residue. Kuhn and Dansi obtained Y-p-tolyl-n-glucosylamine by reaction of Y-(4,5-dimethyl-2-nitrophenyl)-D-glucosylamine with p-toluidine. Further ex-... 

This possible mechanism is applicable only to compounds having a hydrogen atom attached to the nitrogen atom, yet Kuhn and Birkofer found that mutarotation occurs in pyridine solutions of derivatives of secondary amines, namely, n-glucosylpiperidine and iVjiV -dibenzyl-D-glucosylamine, where no such hydrogen atom is available. To explain mutarotation in such cases they postulated the formation of an acyclic imonium ion by expulsion of a proton from a substituted ammonium ion. 

The preparation of crystalline methyl ethers of iV-phenyl- or Af-p-tolyl-aldosylamine by condensation of aniline or p-toluidine with aldose methyl ethers proceeds, in many cases, readily and quantitatively in methanolic or ethanolic solution, either at room or reflux temperature. For this reason, such derivatives are frequently used to characterize aldose methyl ethers isolated during constitutional studies on polysaccharides. For D-glucose, for example, crystalline 2-0-methyl-, 6-0-methyl-,3,4-di-O-methyl-, 2,3,4-tri-O-methyl-, 2,4,6-tri-O-methyl-, " and 2,3,4,6-tetra-O-methyl-A-phenyl-n-glucosylamine have been prepared in this way. Although anomeric forms of A -arylaldosylamine methyl ethers are possible, such anomeric pairs have not been isolated. No similar derivatives have been obtained from ketose methyl ethers. 

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