Fischer glycosidation

Fischer glycosidation (or Fischer glycosylation) refers to the formation of a glycoside by the reaction of an aldose or ketose with an alcohol in the presence of an acid catalyst. The reaction is named after the German chemist, Emil Hermann Fischer, winner of the Nobel Prize in chemistry, 1902, who developed this method between 1893 and 1895. [cite journal
title = Ueber die Glucoside der Alkohole
author = Emil Fischer
journal = Berichte der deutschen chemischen Gesellschaft
volume = 26
issue = 3
pages = 2400–2412
year = 1893
url =
doi = 10.1002/cber.18930260327 ] [cite journal
title = Ueber einige synthetische Glucoside
author = Emil Fischer, Leo Beensch
journal = Berichte der deutschen chemischen Gesellschaft
volume = 27
issue = 2
pages = 2478–2486
year = 1894
url =
doi = 10.1002/cber.189402702248 ] [cite journal
title = Ueber die Verbindungen der Zucker mit den Alkoholen und Ketonen
author = Emil Fischer
journal = Berichte der deutschen chemischen Gesellschaft
volume = 28
issue = 1
pages =1145–1167
year = 1895
url =
doi = 10.1002/cber.189502801248 ]

Commonly, the reaction is performed using a solution or suspension of the carbohydrate in the alcohol as the solvent. The carbohydrate is usually completely unprotected. The Fischer glycosidation reaction is an equilibrium process and can lead to a mixture of ring size isomers, and anomers, plus in some cases, small amounts of acyclic forms. With hexoses, short reactions times usually lead to furanose ring forms, and longer reaction times lead to pyranose forms. With long reaction times the most thermodynamically stable product will result, which owing to the anomeric effect, is usually the alpha anomer.

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Helferich method

The Helferich method is a glycosidation carried out with phenol ["Eine neue Methode zur Synthese von Glykosiden der Phenole1)." (p 378-383) Burckhardt Helferich, Ernst Schmitz-Hillebrecht Berichte der deutschen chemischen Gesellschaft Volume 66 Issue 3 , Pages 321 - 462 1933 DOI|10.1002/cber.19330660313]

References