Aldononitrile acetates from

Poly-O-acetyl-benzothiazol-2-yl acyclo C-nucleosides 184 were prepared in good yields from the aldononitrile acetates (183) [69ACH(62)179 82ACH(109)229] or aldonoyl chloride acetates 38 [69ACH(62)179] by reaction with 2-aminothiophenols (Scheme 54). 

Aldononitrile acetates are suitable for analysis of sugars by g-l.c., and give characteristic mass spectra that are easy to interpret. The molecular ion is not seen, but ions are found at (M — 73) and (M — 98) , corresponding to loss of CH2OAC and CH(OAc)CN moieties, respectively. Primary fragments are formed by a-cleavage of the alditol chain, as depicted in 40. The ions m/e 98 and 170, expected from fission... 

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 a reinvestigation of the synthesis of aldononitrile peracetates from sugars by oximation and acetylation, it was shown that (a) peracetylated acyclic oximes are present in the product mixtures, but are converted to the nitriles by elimination of acetic acid in the heated injection port during GLC analysis and (b) less of the peracetylated A-hydroxyglycosylamine byproduct is formed using 1-methylimi-dazole as a catalyst. The fate of 2,3 5,6-di-0-isopropylidene-D-mannose oxime, which can exist as its cyclic AT-hydroxy-a-D-mannofuranosylamine tautomer, on... 

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). 

Classification of the polysaccharide type is achieved fundamentally by hydrolysis to identifiable sugars, and by methylation analysis, in which the cleavage products from the permethylated polysaccharide are identified and assayed, after conversion to alditol acetates, acetylated aldononitriles, or other derivatives, by GC and GC-MS. Methanolysis of the permethylated polysaccharide and conversion to TMS derivatives is an alternative. The proportions of monosaccharides and their linkage modes are deduced from the molar quantities of sugar methyl ethers derived from the processed polysaccharide... 

G. l.c. of the corresponding peracetylated aldononitriles has permitted 2,3,4- and 2,3,6-tri-O-methyl-D-glucose to be separated for the first time. Chemical-ionization mass-spectral data for most of the possible methylated hexitol acetates that can be derived from D-glucose, o-galactose, and D-mannose have been recorded. Many arrangements of the 0-methyl and 0-acetyl groups can be distinguished on the basis of the chemical-ionization mass spectra. 

A g.l.c. procedure that establishes the DP of oligo- and poly-saccharides has been developed. The oligo(poly)saccharide was reduced prior to hydrolysis and conversion of the reducing sugars liberated into their oxime derivatives the DP was determined from the ratio of acetylated aldononitrile to acetylated alditol. A similar technique, which determined the ratio of aldose acetate to alditol acetate, was used to measure the DP of amylose. ... 

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