Favorskii reaction

The Favorskii reaction ( not to be confused with the Favorskii rearrangement) is a name reaction and named after the Russian chemist Alexei Yevgrafovich Faworski. It is a special case of the nucleophilic attack on the carbonyl groups, wherein a terminal alkyne is used as the CH-acid component.

Reaction mechanism

From an alkyne acetylide is generated in situ, which then reacts with the carbonyl carbon of the carbonyl compound. To this end, strong bases such as hydroxides or alkoxides are usually necessary. If the resulting alcohol has a hydrogen atom geminal to a hydroxy group (which is always the case when an aldehyde is used as the carbonyl compound ), it is almost immediately to a tautomeric rearrangement to the α - Carbonylalken.

The Favorskii reaction can be used to protect alkynes. In this case, either the alkyne with acetone to a (2- hydroxyprop -2 -yl) alkyne or reacted directly used the commercially available 3-methyl- 1- butyn- 3-ol as a unilaterally protected ethyne derivative. To remove the protection group again, in a solution of potassium hydroxide in isopropanol or toluene heated ( " retro - Favorskii reaction ").

If the reaction is acid-catalyzed, it is a Meyer- Schuster rearrangement.