Amino sugars 3-dicarbonyl compounds

The death on October 8, 2009 of Antonio Gomez Sanchez is noted with regret. He was one of the successors of the Seville carbohydrate school built up by Francisco Garcia Gonzalez, with whom he coauthored in Volume 20 a chapter on the reaction of amino sugars with 1,3-dicarbonyl compounds, a subject that was a major theme of Gomez Sanchez s research. 

The first group contains compounds produced in the early stages of the reaction by the breakdown of the Amadori or Heynes intermediates, and includes similar compounds to those found in the caramelisation of sugars. Many of these compounds possess aromas that could contribute to food flavour, but they are also important intermediates for other compounds. The second group comprises simple aldehydes, hydrogen sulphide or amino compounds that result from the Strecker degradation occurring between amino acids and dicarbonyl compounds. 

Garc a GonzAlez, F., and G6mez Sanchez, A., Reactions of Amino Sugars with fteto-Dicarbonyl Compounds, 20, 303-355... 

Maillard reaction products formed by interaction of reducing sugar and amino acids such as a-dicarbonyl compounds, aldehydes, hydrogen sulfide, and ammonia can react further to form derivatives that have been identified from meat or its components during heating. Important reviews of sulfur compounds that might be produced by these reactions have been published by Schutte (35) and... 

Sugars, polysaccharides, polyhydroxycarboxylic acids, reductones, a-dicarbonyl compounds, and quinones will undergo browning in the absence of amino compounds. 

Strecker [34] discovered that the reaction between amino acids (glycine, alanine, leucine) and the tricarbonyl compound alloxan yields CO2 and aldehydes. The Strecker degradation of amino acids occurs also with dicarbonyl compounds [35] including those that are formed in the course of the Maillard reaction, in particular deoxyglycosones and some of the smaller sugar fragments like 7 and diacetyl. Fig. 3.22 shows the reaction pathway that involves the formation of an imine 8, followed by decarboxylation and liberation of the resulting aminoketo compound and the Strecker aldehyde from the intermediate 10. Odour-active Strecker aldehydes which... 

Sialic (neuraminic) acids have structural features in common with compounds assumed to be intermediates in the formation of pyrroles from amino sugars and -dicarbonyl compounds, and some of their properties will be interpreted with this in mind. This article terminates with a discussion of the relationship between these reactions and some biological processes. 

The reaction of 1-amino-l-deoxy-D-fructose with /3-dicarbonyl compounds in aqueous acetone at neutral pH has also been studied. The acetate of this amino sugar affords, with ethyl acetoacetate, ethyl 2-methyl-4-(D-om6wo-tetrahydroxybutyl)pyrrole-3-carboxylate (17). As in previous... 

The reaction of amino sugars with (8-dicarbonyl compounds in alkaline solution produces (tetrahydroxybutyl) pyrroles together with simpler pyrrole compounds lacking the tetrahydroxybutyl side-chain. 2-Amino-2-deoxy-D-glucose hydrochloride and ethyl acetoacetate, heated in aqueous solution at pH 9.7, give a mixture of ethyl 2-methyl-5-(D-ara )mo-tetra-hydroxybutyl)pyrrole-3-carboxylate (1) and ethyl 2-methylpyrrole-3-carboxylate. The yields of these compounds are in the approximate ratio... 

A -Acyl substitution of 2-amino-2-deoxyaldohexoses prevents their reaction with /3-dicarbonyl compounds from giving pyrrole derivatives. Instead, the products of the aldol reaction of the aldehydo form of the sugar with the active methylene group of the /3-dicarbonyl compound are formed. These substances have the structural features of higher-carbon, branched-chain carbohydrates. 

Consideration of the number of bonds affected in the reaction of amino sugars with 8-dicarbonyl compounds (Scheme A X = NH, )V-alkyl, A -aryl) allows the presumption that the mechanism is complex and that,... 

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