Rearrangement, Amadori

D-Aldoses are thus converted into D-ketoses. The reaction is analogous to the ketol isomerization described on page 1061. 

According to Weygand,51 the Amadori rearrangement is catalysed by hydrogen ions, but Hodge and Rist achieved this catalysis by means of sodium salts of CH-acidic compounds.52 

The Chapman rearrangement provides an elegant synthesis of unsymmetrical diarylamines that are otherwise difficult of access. When aryl JV-arylbenz-imidoates are heated, the O-aryl group migrates to nitrogen while the double bond moves from the N=C to the C=0 position. For example, 2,4,6-tri-chlorophenyl iV-(o-chlorophenyl)benzimidoate is converted quantitatively into A-(0-chlorophenyl)-jV-(2,4,6-trichlorophenyl)benzamide when heated for 

Amadori, Atti Reale Accad. Lincei Roma, [vi], 2, 337 (1925). 

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Hodge, J. E. The Amadori Rearrangement. Advances Carbohydrate Chem. 

Figure 1.37 A reducing sugar may modify protein amine groups through Schiff base formation followed by an Amadori rearrangement to give a stable ketoamine product. Glucose is a common in vivo modifier of blood proteins through this process.

Fig. 6.25. Simplified mechanism of two degradation reactions between peptides and reducing sugars occurring in solids, a) Maillard reaction between a side-chain amino (or amido) group showing the formation of an imine (Reaction a), followed by tautomerization to an enol (Reaction b) and ultimately to a ketone (Reaction c). Reaction c is known as the Amadori rearrangement (modified from [8]). b) Postulated mechanism of the reaction between a reducing sugar and a C-terminal serine. The postulated nucleophilic addition yields an hemiacetal (Reaction a) and is followed by cyclization (intramolecular condensation Reaction b). Two subsequent hydrolytic steps (Reactions c and d) yield a serine-sugar conjugate and the des-Ser-peptide...

During the course of the Amadori rearrangement, the 1,2-enolamine intermediate (82) can rearrange to form 3-deoxyhexos-2-ulose (39) under aqueous conditions while releasing the amine or, more importantly, the... 

Scheme 17.—Formation of 3-Deoxyhexo-2-ulose by Way of the Amadori Rearrange- ...

The Maillard condensation is one of the most extensively studied reactions within the field of degradation chemistry, particularly in the area of food and nutritional science. Louis Mallard reported in 1912 that some amines react with reducing carbohydrates to produce brown pigments. The condensation typically yields a simple glycosylamine, which then readily undergoes the Amadori rearrangement to produce 1 -amino-1 -deoxy-2-ketoses [95]. Reducing carbohydrates... 

Amadori rearrangement, 10, 169-205 Amino sugars. See Sugars, 2-amino-2-deoxy. 

Amadori rearrangement to give 1-Dibenzylamino-l-deoxy-D-fructose. . 215... 

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