Aldononitriles partially methylated

B. A. Dmitriev, L. V. Backinowsky, O. S. Chizhov, B. M. Zolotarev, and N. K. Kochetkov, Gas-liquid chromatography and mass spectrometry of aldononitrile acetates and partially methylated aldononitrile acetates, Carbohydr. Res., 19 (1971) 432 135. 

Partially methylated, acetylated aldononitriles are acyclic derivatives readily formed from reducing sugars by reaction with hydroxylamine in pyridine, followed by the addition of acetic anhydride to effect elimination of acetic acid from oxime acetates and acetylation of unsubstituted hydroxyl groups. These derivatives, although less extensively used, appear to give good GLC separations, and their mass spectra can be readily interpreted without the problem of structural symmetry (75MI3). 

Fig. 1 Schematic for the permethylation linkage analysis, exemplified by a hypothetical trisaccharidc, Gal-(a-l,4)-Glc-(a-l,6)-Man. The acid-hydrolyzed partially methylated monosaccharides generated are analyzed by GC-MS, typically as alditol or aldononitrile derivatives...

Secondary fragments were formed by single or consecutive eliminations of acetic acid or ketene, as already described (see Section IV,1 p. 53). Partially methylated aldononitrile acetates have been investigated by Kochetkov and coworkers. They found that this class of compounds is fragmented in a manner analogous to that described for partially methylated alditol acetates (see Section IV,5 p. 58). 

Per-O-acetyl aldononitriles and methylated aldononitrile acetates have been separated by g.I.c. on a mixed liquid phase. Chemical ionization m.s. showed the presence of peaks at M + 1 in each instance. The retention times of a number of partially methylated alditol acetates have been recorded on a variety of stationary phases. Using a combination of silica gel chromatography and g.I.c., fifteen methyl ethers of methyl a-D-galactopyranoside have been isolated from the partial methylation products of D-galactose. ... 

In this paper, we have compared two commonly used permethylation methods [4, 5] and have applied them to a model carbohydrate compound. The completeness of the methylation steps was established by matrix-assisted laser desorption/ionization tlme-of-flight mass spectrometry (MALDI-TOF MS). The methylated carbohydrate products were acid-hydrolyzed and converted to methylated partially acelylated aldononitrile derivatives (Me PAANs) for linkage analysis by gas chromatography-mass spectrometry (GC-MS) [11]. 

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