Faworski reaction
The Faworski reaction (not to be confused with the Faworski rearrangement ) or Faworski- Babayan reaction is a name reaction and named after the Russian chemist Alexei Evgrafowitsch Faworski . It is a special case of nucleophilic attack on carbonyl groups , in which a terminal alkyne serves as the CH-acidic component.
Reaction mechanism
From the alkyne is in situ a acetylide generated is then reacted with the carbonyl reacts carbon of the carbonyl compound. This usually requires strong bases such as hydroxides or alcoholates . If the alcohol obtained has a hydrogen atom geminal to the hydroxyl group (which is always the case when an aldehyde was used as the carbonyl compound), a tautomeric rearrangement to the α- carbonyl alkene usually occurs immediately .
The Faworski reaction can be used to protect alkynes. Either the alkyne is reacted with acetone to form a (2-hydroxyprop-2-yl) alkyne or the commercially available 3-methyl-1-butyn-3-ol is used directly as a unilaterally protected ethyne derivative. In order to remove the protective group again, it is heated in a solution of potassium hydroxide in isopropanol or toluene ("retro-Favorskii reaction").
If the reaction is acid-catalyzed, it is a Meyer-Schuster rearrangement .