Acyl Derivatives of Monosaccharides

Study of the action of ammonia upon carbohydrate acyl esters originated some eighty years ago and, since then, many aspects of this complex reaction have been investigated. The processes that take place in this reaction include migrations, degradations, transesterifications, and deacylations, and their simultaneous occurrence makes the interpretation of the whole scheme very difficult. The present article provides a general description of the facts and a discussion of the different variables that play a role in the yields of products formed and in the mechanisms involved. 

The first study1 on the reaction of a carbohydrate ester with ammonia was performed in 1893 by Wohl, who submitted 2,3,4,5,6- 

For a long time, this reaction was conducted exclusively with acety-lated nitriles of aldonic acids, and the products obtained were known in general as aldose-amides. Fischer2 used this reaction to transform tetra-O-acetyl-L-rhamnononitrile into l,l-bis(acetamido)-l,5-dideoxy-L-arabinitol, whose subsequent hydrolysis and oxidation allowed him to determine the configuration of dextro-tartaric acid (L-threaric acid). 

4 extended this reaction to 2,3,4,5,6-penta-O-acetyl-D-galac-tononitrile (3) and to 2,3,4,5-tetra-O-acetyl-L-arabinononitrile (5), which led to l,l-bis(acetamido)-l-deoxy-D-lyxitol (4) and 1,1-bis-(acetamido)-l-deoxy-L-erythritol (6), respectively. 

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Benzoyl chlorides, like other acyl chlorides, react readily with alcohols to form the corresponding esters (259). The reaction requires 19 h to be completed, and it has been studied in the analysis of carbohydrates, aminosugars, and glycosides (260). Because the preparation of acyl derivatives of monosaccharides is difficult, phenyldimethylsilyl chloride has been also investigated as an alternative label (261). After dissolving the analytes in dimethylformamide and addition of... 

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