Mannopyranosyl bromide

Similarly, the mannopyranosyl analog (346) was synthesized by condensation of di-O-isopropylidene-a-DL-carba-mannopyranose (349) with 348. The other isomer (347) was obtained by reaction of 278 with tetra-O-benzoyl-a-D-mannopyranosyl bromide (350). The four carba-glucopyrano-syl D-mannopyranosides, including 346 and 347, show no antiviral activity. 

The compound of Micheel and Micheel was obtained in small amount after treatment of 2,3,4,6-tetra-O-acetyl-a-D-mannosyl bromide with tri-methylamine the bulk of the material remained unchanged. The product apparently resulted from hydrolysis by moisture from the air. The composition was established by analyses, but the identification was reported with a question mark. A 2,3,4,6-tetra-O-acetyl-D-mannose with different physical constants (m.p. 93°, [c ]d +26.3°) was obtained by Levene and Tipson63b by the deliberate addition of water and silver carbonate to tetra-O-acetyl-D-mannopyranosyl bromide its structure was confirmed by conversion to the known pentaacetates. If Micheel and Micheel were correct in their identification, the two acetates could be anomers. The acetylation and deacetylation reactions performed by Maurer and Bohme are additional evidence in favor of this relationship. 

These workers obtained the unusual a-glycoside when they used the tetra-benzoyl-a-D-mannopyranosyl bromide as the acylglycosyl halide without an acid-acceptor. 

Triacetyl-0-D-arabinopyranosyl bromide Triace tyl-fl-n-arabinopyranosyl bromide Triacetyl-a-ir-rhamnopyranoayl bromide Triacetyl-a-D-ribosyl bromide Triace tyl-a-n-ribosyl bromide Triacetyl-a-D-xylopyranosyl bromide Triacetyl-a-n-xylopyranosyl bromide Tetraacetyl-of-D-galactopyranosyl bromide Tetraacetyl-a-D-glucopyranosyl bromide Tetraacetyl- -D-glucopyranosyl fluoride 2,3 5,6-diisopropylidene-a-D-mannofuranosyl chloride Tetraacetyl-a-D-mannopyranosyl bromide Heptaacetyl-a-cellobiosyl bromide Heptaacetyl-a-gentiobiosyl bromide Heptaacetyl-a-lactosyl bromide Heptaacetyl-a-maltosyl bromide... 

Heptaacetyl-[4-(j3-D-glucopyranosyl)-a-i>-mannopyranosyl] bromide Heptaaeetyl-[6-(/S-D-mannopyranosyl)-o-D-glucopyranosyl] bromide Decaacetyl-[6-(/3-ceUobiosyl)-a-D-glucopyranosyl] bromide Decaacetyl-[6-(/S-gentiobiosyl)-a-D-glucopyranosyl] bromide Decaacetyl-[6-(/3-lactosyl)-a-D-glucopyrano8yl] bromide... 

For the hydrogen bromide elimination an E2 mechanism was considered, as tetra-O-acetyl-a-D-mannopyranosyl bromide and tri-O-acetyl-a-o-rhamno-pyranosyl bromide, which contain the bromine atom and 2-acetoxy group in the trans positions, could not be dehydrobrominated. 

R. K. Ness, H. G. Fletcher, Jr., and C. S. Hudson, The reaction of 2,3,4,6-tetrabenzoyl-a-D-glucopyranosyl bromide and 2,3,4,6-tetrabenzoyl-a-D-mannopyranosyl bromide with methanol. Certain benzoylated derivations of D-glucose and D-mannose. J. Am. Chem. Soc. 72 2200 (1950). 

Mol. wt. 107.15, sp. gr. 0.923, b.p. 142-143°. Suppliers A, B, E, F, KK, MCB. Mazurek and Perlin found this pyridine homolog superior to silver carbonate, the usual acid acceptor, for the preparation of orthoesters (3) from 2,3,4,6-tetra-O-acetyl-a-D-mannopyranosyl bromide (1). Of considerable interest is the fact that... 

Figure 6.32 Successes and failure of carbonate protection in an attempt to make aryl P-mannobiosides. The formation of the cyclic orthocarbonate must be entirely due to the complex phosphine oxide leaving group in the Mitsunobu reaction, since 4,6-di-O-acetyl-a-D-mannopyranosyl bromide 2,3-carbonate gave the expected aryl P-mannosides on reaction -with phenoxides. ...

Bock, I. Lundt, C. Pedersen, and H. Pedersen, Glycosylation reactions with di-O-acetyl-2,6-dibromo-2,6-dideoxy-a-D-mannopyranosyl bromide. A simple synthesis of methyl 2,6-dideoxy-D-arabino-hexopyranoside, Acta Chem. Scand., B42 (1988) 640-645. 

Using the Helferich modification of the Koenigs-Knorr reaction, methyl 4,6-0-benzylidene-o -D-mannopyranoside has been treated with tetra-O-acetyl-a-D-mannopyranosyl bromide, yielding methyl 3-<7-0 -D-mannopyranosyl-a -D-mannopyranoside. Benzyl 2,4-di-0-benzyl-Q -D-mannopyranoside has been... 

A soln. of p-iodobenzyl alcohol and 2,6-lutidine in chloroform added to 2,3,4,6-tetra-O-acetyl-a-D-mannopyranosyl bromide, and stored 24hrs. at room temp. 3,4,6-tri-0-acetyl-/ -D-mannopyranose 1,2- (p-iodobenzyl orthoacetate). Y 69%. F. e. s. M. Mazurek and A. S. Perlin, Can. J. Chem. A3, 1918 (1965) with tetra-n-butylammonium bromide in spm-collidine s. R. U. Lemieux and A. R. Morgan, Gan. J. Ghem. 43, 2199. 

Tetra-Ac 2,3,4,6-Tetra-O-acetyl-i D-mannopyranosyl bromide, 9CI, SCI. Acetobromomannose [13242-53-0]... 

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