Hexoside, methyl anhydro

Based on the fact that methyl 2,3-anhydro-a-D-mannopyranoside (II) is hydrolyzed17 by sodium methoxide to give, on subsequent methyla-tion, a mixture of two methyl trimethyl hexosides (methyl 3,4,6-trimethyl-a-D-altropyranoside and methyl 2,4,6-trimethyl-a-D-glucopyranoside) it was anticipated that the action of ammonia on II would follow essentially the same course. This was found to be the case, for with ammonia II yielded compounds which were converted to methyl 4,6-dimethyI-3-aeetamido-a-altropyranoside (III) and methyl 4,6-dimethyl-2-acetamido-a-D-glucopyranoside (IV) (10% yield). 

Anhydro-3,4-O-isopropylidene-2-O-toayl-/3-D-altrose Methyl 2,0-dideoxy-3-O-methyl-4-O-tosyl-a-D-xylo-hexoside Methyl 2,6-dideoxy-3-0-methyl-4-0-tosyl-/3-D- ct/lo-hexoside 0-Deoxy-2,3-O-isopropylidene-l-O-tosyl-L-sorhose 2,4 3,5-Di-0-methylene-l-0-tosyl-D-epirhamnitol... 

Although hydrolysis of methyl 3,4,6-tri-O-acetyl-a-D-glucoside 2-nitrate leads to the formation of only 2 % of nitrite ion, the reaction appears to be complex. No pure product was isolated, but the resulting sirup (from its analysis and its resistance to oxidation by periodate) was considered to be essentially a mixture of methyl anhydro-a-D-hexosides. Cautious interpretation of these results gave reason for believing that the nitrate group on C2 had been removed like a similarly situated sulfonate group. 

Vis and Karrer114 have found that treatment of methyl 4,6-O-benzyl-idene-2,3-O-p-tolylsulfonyl-a-D-glucoside (13) with lithium aluminum hydride provides methyl 4,6-0-benzylidene-3-deoxy-a-D-n 6o-hexoside (IS) in good yield. Since hydrogenolysis is possible at both C-2 and C-3 of the two possible 2,3-anhydro derivatives, only the alio isomer (14) could give the 3-deoxy derivative by further reaction with a reagent. Indeed, none of the alternative 2-deoxy derivative was found. This transformation is, un-... 

The first of these methods involves the reaction of triphenyl phosphite methiodide with methyl 3-0-methyl-2-0-p-tolylsulfonyl-a-D-glucopyrano-side, hydrogenation of the resulting 4,6-diiodo derivative, and hydrolysis,186 as adapted to monosaccharides by Kochetkov and coworkers.1,0 In another approach,281 ethyl 2,3-anhydro-4,6-dideoxy-D-nbo-hexopyranoside, obtained from desosamine, was treated with sodium methoxide, to give a mixture of 2- and 3-methyl ethers. After fractionation and separation of side products,288 the 3-methyl ether was hydrolyzed, to give crystalline chalcose. McNally and Overend800 have described another synthesis, starting from methyl 4-deoxy-D-xj/Zo-hexoside.107... 

From these experiments it appears that the splitting of the ethylene oxide ring of methyl 2,3-anhydro-4,6-benzylidene-hexosides occurs in the same way both with sodium methoxide and sodium thiomethoxide (sodium methylmercaptide) and reaction occurs according to the follow-... 

The action of hydrochloric and hydrobromic acids on methyl 2,3-anhydro-4,6-benzylidene-a-D-alloside was studied by Newth, Overend and Wiggins.176 Each reagent was shown to produce two distinct methyl halogeno-desoxy-a-D-hexosides. Hydrobromic acid gave methyl 2-bromo-2-desoxy-a-D-altroside and methyl 3-bromo-3-desoxy-a-D-glu-... 

From the account already given of the methods employed for the preparation of desoxyhexose derivatives by the action of various reagents on 2,3-anhydro derivatives of methyl hexosides, it is apparent that... 

The tosyl esters react like the halogen compounds. Methyl 4-tosyl-2,3,6-triacetyl- 9-D-glucopyranoside (XLVIII), which may be obtained from methyl 6-trityl-/3-D-glucopyranoside (see page 92), did not give a 4-tosyl derivative even on very careful deacetylation. The sulfonic acid residue was split off simultaneously and a peculiar anhydride was formed. Mtiller suggested a methyl 3,4-anhydro-n-hexoside structure (XLIX) for this substance. 

A standard displacement with azide ion, etc., has been used in the conversion of 3,4,7-tri-0-acetyl-2,6-anhydro-5-0-methanesulphonyl-D- /ycero-L-ma/jno-heptonamide (113) into 5-amino-2,6-anhydro-5-deoxy-D- /> ccro-D- w/<7-heptonic acid (114), which, after formation of the methyl ester hydrochloride, underwent polycondensation to give oligomeric or polymeric amides on treatment with methanolic sodium methoxide. Both 3-acetamido-2,3,6-trideoxy-L-hexosides (116) and (117) have been synthesized by introduction of an amino-group via azide-displacement of the allylic acetoxy-group in the glycal derivative (115) (116) and (117) are derivatives of L-acosamine and L-ristosamine, respectively. ... 

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