Alditols isolation

A preparation of l,5-dideoxy-l,S-imino-D-allitol from A protected deoxynqjirimycin v ch involves a microbial redox reaction at C-3 has been described, and the glycosidase inhibitory properties of the product were determined together with those of other imino-alditols isolated from the leaves of Mens alba (see also ref 40 above). ... 

Efforts were made by Garcia Gonzalez and his coworkers to elucidate the mechanism of this reaction. In one of the working hypotheses, it was considered that the aldehydo form of the sugar and the 1,3-dicarbonyl compound undergo an aldol reaction to yield a 2-C-(alditol-l-yl)-l,3-dicar-bonyl compound, which is then dehydrated to form the furan. This hypothesis was supported by the isolation of the aldol-addition product of... 

In a study completed during the early development of f.a.b.-m.s., both f.d. and f.a.b. were used to characterize 101 fractions containing neutral oligosaccharides isolated from human milk. Samples were examined as their peracetylated alditols. In subsequent work, the structures of two minor acidic oligosaccharides from human milk were investigated. The per-methylated derivatives were analyzed by f.a.b.-m.s., and their compositions and sequences were defined by the f.a.b. data. Methylation analysis and partial formolysis were the other principal methods used. 

Oligosaccharides were isolated from PMII by weak acid hydrolysis and separation by SEC and HPAEC-PAD. The isolated oligosaccharides were desalted, reduced and methylated. GC-MS analysis of the partially methylated alditol acetates has been used to reveal the structure of the oligosaccharides. 

L. E. Fellows, E. A. Bell, D. G. Lynn, F. Pilkiwicz, I. Miura, and K. Nakanishi, Isolation and structure of an unusual cyclic amino alditol from a legume, J. Chem. Soc., Chem. Commun. (1979) 977-978. 

The Hines64 showed that, as acids, ethanol, isopropyl alcohol, and tert-butyl alcohol are weaker than water, whereas methanol is stronger. The influence of the solvent could thus be interpreted in terms of equation 1. In methanol, the equilibrium would be more displaced to the right, and the rate of simple ammonolysis and transesterification would be enhanced, with concomitant decrease in the yields of amido sugars. In water (for the ammonolysis of sugar acetates) and in alcohols other than methanol, the equilibrium would be displaced to the left and this would allow operation of the orthoester mechanism a better chance. The isolation, from the reaction in isopropyl alcohol, of mono-O-benzoylated bis(benzamido)alditols, could also be explained on this basis. 

The more stable boron chelates can be isolated even from aqueous solution, whereas those of lower stabilities are only accessible from non-aqueous media. Catechol- and inositol-borates (3, 5 and 6) possesses a well-defined monomeric structure,75 whereas those obtained from monosaccharides and alditols are polymeric.121 A crystal structure determination122 has been carried out for sodium scyUo-inositol diborate (6). 

Air classification, starch isolation, 674-675 Aldehydes, see also Carbonyl compounds citrus oils, quantification meats, effect on flavor, 559 Alditol acetates... 

CD. see Circular dichroism Cell wall polysaccharides isolation of plant cell walls and fractionation, 697-718 neutral sugars, determination by GC of alditol acetates, 721 -732 pectin... 

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