Amino sugars reaction with methanol

The preparation of several glucofuran [2, l-t/] oxazolines 35 and 36 from reaction of 2-amino-2-deoxy-D-glucose 34 with HF has been described. Compounds 35a and 35b are formed when the reaction is carried out in formic acid, whereas the orthoesters 36a-c are formed when the reaction is carried out using anhydrides. Further reaction of 35 and 36 with methanol gives methyl glycosides. Thus, 35 and 36 may hnd use as potential glycosyl donors for the synthesis of 2-amino-2-deoxy sugars (Scheme 8.14). " ... 

The preparation of aziridines and substituted aziridines from a number of sugars that contain substituted amino groups has been described. With such compounds as the sulfonamide (241) and the cyanamide (231), where the functional groups are fmns-diaxial, aziridine formation is the expected course of the reaction under alkaline conditions. Baker and Hullar described the conversion of (241) into the substituted aziridine (188, R = Ts) with methanolic sodium methoxide at room temperature similar transformation of (231) into (242) was accomplished with alcoholic... 

Base-catalyzed reactions of amino sugars with 2,4-pentanedione in a nonaqueous solvent (piperidine-triethylamine-methanol) have also been reported. The products obtained under these conditions from 2-amino-2-deoxy-D-glucose are 3-acetyl-2-methyl-5-(D-ami)OTo-tetrahydroxybutyl)-pyrrole (2) (in about 90% yield) and 2-deoxy-2-n(4-oxopent-2-enyl)-amino]-D-glucose (28). Proofs that structure (28) is correct were (a) the ultraviolet absorption, typical of a -amino a,j3-unsaturated ketone, (b) a positive test with the ferric chloride reagent, and (c) quantitative... 

This reaction was first reported by MacDonald and Fischer in 1952. It is the degradation of hexoses into pentoses involving the steps of formation of dithioacetal, oxidation to unsaturated disulfone by means of perphthalic acid, hydrazine treatment, and benzalde-hyde splitting of the corresponding hydrazone. Therefore, the whole process is known as the MacDonald-Fischer degradation. In addition, when the unsaturated disulfone is dissolved in aqueous ammonia or methanol saturated with ammonia, 2-deoxy-2-amino sugar is resolved. This reaction in combination with mass spectroscopy was used to study the structure and stereochemistry of carbohydrates. ... 

Davis and coworkers carried out a Wittig-cyclization sequence with the partially protected 2-deoxyamino sugar 191 using an amino acid based phosphonate. Reaction of 191 with the cesium enolate 192 gave a 53% yield of epimers 193 and 194 (1 1 ratio) in which epimerization of the 2-amino group had taken place. The maimo isomer 194 was then epimerized to the more stable gluco 193 derivative by simple treatment with t-BuOLi in methanol (Scheme 38) [54]. 

The method is unspecific, but allows the determination of a-diols, polyols, and a-amino alcohols in the presence of simple alcohols (e.g. methanol or ethanol). Ethyleneglycol, giyceroF or sugars and serine can be determined using either an acetate pH 4-7 buffer ) or a phosphate pH 7 buffer, ) or solutions simply acidified with periodic acid, ) both as a reaction medium and as a supporting electrol3rte. 

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