2-Amino-2-deoxy-a-D-glucopyranosyl bromide

For the synthesis of the a-phosphate, 3,6-tri-0-acetyl-2-amino-2-deoxy-a-D-glucopyranosyl bromide hydrobromide (22) was condensed, according to Maley et al. 

Methyl 2-Deoxy-2-sulfoamino-j8-D-glucopyranoside Trisulfate and the Preparation of Tri-0-acetyl-2-amino-2-deoxy-a-D-glucopyranosyl Bromide, M. L. Wolfrom and T. M. Shen Han, . Org. Chem., 26, 2145-2146 (1961). 

Coupling of 237 with the protected 2-amino-2-deoxy-o -D-glucopyranosyl bromide (348) in dichloromethane in the presence of silver triflate afforded a diastereoisomeric mixture. The isomer related to the natural one was depro-tected with sodium in liquid ammonia, to give the carba-trehalosamine... 

For the 2-phenyloxazolines, the reaction is performed, for example, by treating tri-0-acetyl-2-benzamido-2-deoxy-a-D-glucopyranosyl bromide (134) with hydrobromic acid158- 184 to give 135. Alternatively, the unacetylated 2-acylamido-2-deoxy-D-glucose is treated with hydrochloric acid in acetone, and the 5,6-isopropylidene acetal (136) is obtained.165 Compound 136 has proved a valuable intermediate in the synthesis of several amino sugars.186- 172... 

Tri-Ac 3,4,6-Tri-0-acetyl-2-amino-2-deoxy-x-D-glucopyranosyl bromide CijHigBrNOy 368.181 Mp 149-150° (as hydrochloride). [a]o + 148.4 (MejCO). 

Acetamido-3,4,6-tri-0-acetyl-2-deoxy-a-D-glucopyranosyl bromide can also be used,71 but the more stable chloride is preferred for general use, as the bromide is unstable and changes to 1,3,4,6-tetra-0-acetyl-2-amino-2-deoxy-D-glucopyranose hydrobromide during isolation.72-75 Furthermore, a 3,4,6-tri-0-acetyl-2-(acylamido)-2-deoxy-a-... 

FIGURE 7.14 Activated esters for temporary protection and activation of Fmoc-amino acids for the synthesis of glycopeptides. (A) Reaction of a-D-glucopyranosyl bromide with esterified Fmoc-serine. (B) Reaction of 2-acetamido-2-deoxy-3,4,6-triacetyl- 3-D-glucopyranosyl amine with esterified Fmoc-aspartyl chloride.37-38 Pfp = pentafluorophenyl. 

The first poly-O-acetylaldosyl azide was synthesized by Bertho by treating tetra-O-acetyl-a-D-glucopyranosyl bromide with a metal azide. In addition to the aldosyl azide derivatives that are known (see Table IV), derivatives of 2-amino-2-deoxy-D-glucosyl azide have been prepared - (see Table V). If the trans hydroxyl group at C-2 is not acetylated, an intermediate epoxide of the type suggested for the aldosyl fluorides can form, and the azide obtained has the. same anomeric configuration as the original halide, as. shown by the formulas. The acetylated azides, like the... 

It is noteworthy that the formation of the 5-glycoside 116 is compatible with the formation of 115 by an add-reversion reaction, and difiFers from the situation obtaining in the condensation - of tetra-O-acetyl-a-D-glucopyranosyl bromide [or 2,4,6-tri-0-acetyl-3-(bens5yloxycar-bonyl)amino-3-deoxy-a-D-glucopyranosyl bromide or 2,3,4-tri-0-acetyl-6-(benzyloxycarbonyl)amino-6-deoxy-o-i>-glucopyranosyl chloride] with N,N -di(benzyloxycarbonyl)-2-deoxystreptamine that yielded 4,6-di-O-j9-D-glycosides. 

The radical formed by detachment from the anomeric hydroxyl group is indicated by replacing the final letter e by yl as in bromide 4.21 or dipotassium phosphate 4.22 of tetra-O-acetyl-a-D-glucopyranosyl. In the case of a replacement by an amino group, the suffix amine is added, as in 2-acetamido-2-deoxy-j3-D-glucopyranosylamine 4.23. 

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-... 

An improved synthesis of paromamine was effected with a Schiff base and a more protected 2-deoxystreptamine. The cyclohexylidene derivative of l,3-di-2V-(ethoxycarbonyl)-2-deoxystreptamine (79, race-mate) was condensed with 3,4,6-tri-0-acetyl-2-deoxy-2-(p-methoxy-benzylideneamino)-a-D-glucopyranosyl bromide (see Refs. 174 and 175 on p. 153) to give two products (80 and 81), which, after removal of the protecting groups, furnished paromamine (78) and an isomer, 6-0-(2-amino-2-deoxy-o-D-glucopyranosyl)-2-deoxystreptamine (82). The latter was devoid of antibacterial activity. 

Considerable attention has been given to amino-sugar disaccharides. The 2-azido-2-deoxyglycosyl chloride procedure has been applied to obtain 2-amino-2-deoxy-a-D-glucopyranosyl a-D-glucopyranoside (trehalosamine)/ and the 2-deoxy-2-phthalamidoglycosyl bromide method to produce 6-0-(2-acetamido-... 

Racemic (l,3/2)-l-benzyloxycarbonylamino-3-0-ethyl- and (l,2/3)-3-benzyl-oxycarbonylamino-l-O-ethyl-cyclohexanediols (prepared from 3-ethoxycyclo-hexene) have been condensed under Koenigs-Knorr conditions with 3,4,6-tri-O-acetyl-2-deoxy-2-(2,4-dinitrophenyl)amino-a-D-glucopyranosyl bromide to yield... 

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