Rearrangement amadori

Amadori rearrangement - isomerization of aldose N- glycosides to 1-amino-1-deoxyketosis. Opened by Italian chemist .

Amadori's rearrangement is catalyzed by acids and proceeds through the intermediate formation of aldimine , which is formed during the opening of the pyranose cycle of N-glycoside 1 and acid catalyzed tautomerization of imine 3 to 2- hydroxyenamine (or, equivalently, 2- aminoenol ) 4 , which, in turn, tautomerizes in 2-oxoamine - 1-amino-1-deoxyketosis 5 :

The rearrangement of the Amadori type is also characteristic of Schiff bases derived from glycerol aldehyde :

R-CH (OH) CHO + R'NH ₂${\displaystyle <span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">\to </span></span>}$ {\ displaystyle \ to} R-CH (OH) CH = NR '+ H ₂ O

R-CH (OH) CH = NR '${\displaystyle <span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">\to </span></span>}$ {\ displaystyle \ to} R-COCH ₂ NHR '

N-glycosides of primary aromatic amines are most easily regrouped, ^[1] Amadori rearrangement also occurs in the case of glycosyl derivatives of primary and secondary aliphatic amines.

Amadori's rearrangement is used in the chemistry of carbohydrates to convert aldoses into ketoses; for this, 1-amino-1-deoxyketoses derived from ketosis and primary amines are deaminated by the action of nitrous acid; for example, fructose can be synthesized from glucose.

Amadori's rearrangement is also the first stage of the Maillard reaction between aldoses and amino acids, which leads to the formation of dark-colored products (melanoidins) during cooking.

Under conditions of ketosis, N-glycoside ketosis undergoes a rearrangement by a similar mechanism into 2-amino-2-deoxaldose (Amadori retro-grouping, or Hynes's rearrangement ).