Glucose nitrous acid deamination

Scheme 2. — Nitrous Acid Deamination of 2-Amino-2-deoxy-D-glucose and Its Glycosides.

The nitrous acid deamination of 2-amino-2-deoxy-D-mannose (8), in the favored conformation, the amino group ofwhich is axially attached, leads, in contrast, uniquely to D-glucose,15 characterized, after oxidation by nitric acid, as D-glucaric acid (9). This result has also been verified by direct crystallization of the D-glucose and by assay with D-glucose oxidase.44"... 

In attempting to obtain 2,5-anhydro-D-glucose diethyl dithioacetal, Defaye58 performed the nitrous acid deamination of 2-amino-2-deoxy-D-glucose diethyl dithioacetal (27) under weakly acidic conditions (acetic acid and sodium nitrite), and obtained a principal product later shown59 to be ethyl 2-S-ethyl-l,2-dithio-a-D-mannofuranoside (28). Shortly before, Horton and coworkers60 had reported the forma-... 

This reaction has been compared81 with the nitrous acid deamination of 2-amino-2-deoxy-D-glucose attack by a bromonium ion could lead to an intermediate, alkyl-iodonium cation (2-C-I-Br) , which would decompose through nucleophilic attack by 0-5, which is antiparallel to the leaving group at C-2. 

D. Horton and K. D. Philips, The nitrous acid deamination of glycosides and acetates of 2-amino-2-deoxy-D-glucose, Carbohydr. Res., 30 (1973) 367-374. 

A sensitive fluorimetric assay for 2-amino-2-deoxy-D-hexoses with increased sensitivity over the Elson-Morgan and Dische-Borenfreund indole methods has been reported. The 2,5-anhydrohexoses produced by nitrous acid deamination of heparin, heparan sulphate, and 2-amino-2-deoxy-D-hexoses have been treated with 3,5-diaminobenzoic acid to give stable derivatives. Neither neutral sugars nor acetamido sugars interfere in the reaction. In a modification of an earlier procedure, equivalent colour complexes were formed by the interaction of 3-methyl 2-benzothiazoline and the 2,5-anhydrohexoses produced by deamination of 2-amino-2-deoxy-D-glucose and 2-amino-2-deoxy-D-galactose. ... 

Application of nitrous acid deamination to the naturally occurring chitosamine 45) (2-amino-2-deoxy-D-glucose) provided Fischer and Tie-mann 46) with the first recorded example of a hydrofuran anhydro sugar. The sirupy product, chitose, could be oxidized to give, successively, an... 

More-specific methods are available for identifying and quantitating the typical, amino sugar component of heparin (and some heparan sulfate species), namely, 2-deoxy-2-sulfoamino-D-glucose. Most of these methods are based on conversion of these residues into 2,5-anhydro-D-mannose by deamination with nitrous acid (see Section VIII,2). The 2,5-anhydro-D-mannose residues may be determined either colorimetrically,52-54 or fluorimetrically.55... 

In analogy with the deamination of aminocyclohexanes,17-21 it has been found that the deamination, with nitrous acid, of 2-amino-2-deoxyaldohexoses in which the amino group has an equatorial orientation leads to 2,5-anhydrohexoses, as exemplified by the deamination of 2-amino-2-deoxy-D-glucose (10) to 2,5-anhydro-D-mannose22-25 (11). 

As acetamido groups do not react with nitrous acid under the usual conditions, it was possible to identify 2-acetamido-2-deoxy-D-glucose residues in heparin after deamination,244 and their distribution was... 

Deamination of the hexosamine molecule occurs on heating it with alkali,205 and determination of the ammonia evolved is the basis of one quantitative method for the determination of 2-amino-2-deoxy-D-glucose.206 Deamination of 2-amino-2-deoxy-D-glucose with nitrous acid leads to the formation of 2,5-anhydro-D-mannose ( chitose ), which can be isolated as the crystalline diphenylhydrazone.207 Reduction of 2,5-anhydro-o-man-... 

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