Mannopyranoside methyl 3,6-anhydro

Mannonic acid, 3-deoxy-D-, 75, 300 Mannopyranose, d-, oxidation of, 12 —, l,6-anhydro-/3-D-, 51 Mannopyranoside, methyl 3,6-anhydro-D-, 39... 

Methylation of methyl 3,4-anhydro-a-DL-talopyranoside, followed by acid-catalysed opening of the oxiran ring, has been used in a synthesis of methyl 2,6-di-O-methyl-a-DL-mannopyranoside (methyl oL-curamicoside). Ringopening of methyl 3,4-anhydro-6-0-trityI-DL-allopyranoside with ammonia etc., afforded derivatives of OL-kanosamine (3-amino-3-deoxy-DL-glucose). 

Ci4HlfiOs Methyl 2,3-anhydro-4,6-0-benzylidene-a-D-mannopyranoside MABMPY 30 454... 

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). 

In 1938, Lake and Peat168 reported that methyl 2,3-anhydro-4,6-dimethyl-/3-D-mannopyranoside (prepared from methyl 2-tosyl-3,4,6-triacetyl- S-D-glucopyranoside by detosylation with sodium methoxide and subsequent methylation)164 gave rise, when boiled with sodium methoxide in methyl alcohol, to almost equal proportions of methyl... 

Stoicheiometric RuOyCCl was also used to oxidise several furanoses, partially acylated glycosides and l,4 3,6-dianhydrohexitols [317] pyranosides to pyrano-siduloses [313] methyl 2,3,6-tri-O-benzoyl-a-D-glucopyranoside and its C-4 epimer to the a-D-xy/o-hexapyranosid-4-ulose (Table 2.3) [317], and methyl 2,3,6-trideoxy-a-D-e 7f/tro-hexapyranoside to the -a-D-,g/yceri9-hexa-pyranosid-4-ulose, an intermediate in the synthesis of forosamine [318], It was also used to oxidise benzyl 6-deoxy-2,3-0-isopropylidene-a-L-mannopyranoside to the a-L-/yxo-hexapyranosid-4-ulose [319] and for oxidation of isolated secondary alcohol functions, e.g. in the conversion of l,6-anhydro-2,3-0-isopropylidene-P-D-man-nopyranose to the-P-D-/yxo-hexa-pyranos-4-ulose mannopyranose (Fig. 2.16, Table 2.3 [20, 320, 324]). 

Varma62 synthesized the corresponding l,3-anhydro-2,4,6-tri-0-benzyl-j8-D-mannopyranose from methyl 3-0-allyl-2,4,6-tri-0-benzyl-a-D-mannopyranoside similarly, with some variation in the method. Elimination was not a significant problem in this synthesis, as a trans-diaxial relationship for H-2 and the halogen is not possible. 

The deamination of methyl 3-amino-3-deoxy-/3-D-altropyranoside was studied in 1934, but the products were not fully characterized.14411 The syrupy product was converted into a methylated derivative that had an elemental analysis corresponding to that calculated for a methyl tetramethylhexoside. The conditions used for methyl-ation would have opened an epoxide ring. Methyl 2,3-anhydro-4,6-0-benzylidene-a-D-mannopyranoside precipitated quantitatively from solution when the corresponding 3-amino-3-deoxyaltroside derivative was deaminated in aqueous medium.145 Epoxide formation was likewise reported to be quantitative in the deamination of the analogous 2-amino-2-deoxyaltroside.83 145 On deamination, 4-amino-l,6-anhydro-4-deoxy-/3-D-mannopyranose also gave an epoxide, namely, 1,6 2,3-dianhydro-/3-D-talopyranose, in unspecified yield.146... 

This stabilizing effect of another ring has also been shown in thermal reactions. Bishop, Cooper, and Murray16 injected methyl 3,6-anhydro-a-D-mannopyranoside ihto a gas chromatograph, operating at a column temperature of 225°, and found 75% conversion into the furanoside. 

Since the introduction of lithium aluminum hydride for the cleavage of sugar epoxides,M its use in this route to 3-deoxy sugars has become the method of choice. Thus, treatment of methyl 2,3-anhydro-4,6-0-benzyli-dene-a-D-mannopyranoside with lithium aluminum hydride affords methyl... 

Page 168, line 4. Change to read . . . methyl 2,3-anhydro-4,6-dimethyl-a-D-mannopyranoside (II) is hydrolyzed17 by sodium methoxide to give a mixture of. .. Change formula II accordingly. 

Since the trimethylglucose has been shown to form a 6-lactone, characterized by its rapid mutarotation in aqueous solution,161-163 and to give rise when methylated and hydrolyzed to 2,3,4,6-tetramethyl-D-gluco-pyranose,189 it follows that C5 is unsubstituted. While it is clear that the third methoxyl group must be present on C6, little direct evidence is available to support this view. The syntheses of the trimethylglucose from methyl 2,3-anhydro-/3-D-mannopyranoside (known to condense with benzaldehyde and therefore to carry free hydroxyl groups on C4 and C6)168 and also from 3-benzyl-D-glucose162 leave, however, no doubt that C6 is methylated. 

V. S. Murthy, A. S. Gaitonde, and S. P. Rao, One-pot conversion of 1,2-diols to epoxides —convenient preparation of methyl 2,3-anhydro-5-0-trityl-/ -D-lyxofuranoside and methyl 2,3-anhydro-4,6-0-benzylidene-a-D-mannopyranoside, Synth. Common., 23 (1993) 285-289. 

P. Koll and H. Komander, Methyl-2,6-anhydro-a-D-mannofuranosid, ein Nebenprodukt der Methanolyse von Methyl-2,6-anhydro-a-D-mannopyranosid, Liebigs Ann. Chem., (1981) 1960-1966. 

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