- Amadori rearrangement
The Amadori rearrangement is an
organic reaction describing the acid or base catalyzedisomerization orrearrangement reaction of the N-glycoside of analdose or theglycosylamine to the corresponding 1-amino -1-deoxy -ketose . [ W. Amadori, Atti. reale accad. nazl. Lincei, [6] 2, 337 (1925); [6] 9, 68, 226 (1929); [6] 13, 72 (1931)] ["Strategic Applications of Named Reactions in Organic Synthesis (Paperback)" by Laszlo Kurti, Barbara Czako ISBN 0-12-429785-4] The reaction is important incarbohydrate chemistry .The
reaction mechanism is demonstrated starting from the reaction of D-mannose in its closed (1) and open-form (2) withammonia the 1,1-amino-alcohol 3 which is unstable and loses water to theglycosylamine (again the openimine (5) and the closed formhemiaminal (4)) which is the starting point for the actual Amadori rearrangement. ["Mutarotation, Hydrolysis, and Rearrangement Reactions of Glycosylamines" HORACE S. ISBELL and HARRIET L. FRUSH "J. Org. Chem. " 1958, "23(9)", 1309 - 1319. (DOI|10.1021/jo01103a019)]By treatment of the glycosylamine with
pyridine andacetic anhydride the imine group rearranges and the intermediateenol in turn rearranges to theketone . In this particular reaction the allalcohol andamino groups are acylated as well.The reaction is associated with the
Maillard reaction with reagents naturally occurring sugars andamino acid s.Amadori product
An Amadori product is an intermediate in the production of an advanced glycation end-product (AGE) as a result of
glycation .The formation of an advanced glycation end-product involves the following steps:
# "Formation of aSchiff base ": For example thealdehyde group of aglucose molecule will combine with theamino group of alysine molecule (in aprotein ) to form animine or Schiff base, which is a double bond between thecarbon atom of the glucose and thenitrogen atom of the lysine.
# "Formation of an Amadori product": The Amadori product is a re-arrangement from the Schiff base wherein thehydrogen atom from thehydroxyl group adjacent to the carbon-nitrogen double bond moves to bond to the nitrogen, leaving aketone .
# "Formation of an advanced glycation end-product (AGE)": The Amadori product is oxidized, most often bytransition metal catalysis .The first two steps in this reaction are both reversible, but the last step is irreversible.
External links
* [http://www.cfs.purdue.edu/class/f&n630/amadori_rearrangement.ppt Play by play Amadori rearrangement and more]
References
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