Favorskii reaction

The Favorskii reaction (not to be confused with the Favorskii rearrangement), named for the Russian chemist Alexei Yevgrafovich Favorskii, is a special case of nucleophilic attack on a carbonyl group involving a terminal alkyne with acidic protons.



When catalyzed by acid, this reaction is called the Meyer-Schuster rearrangement.

Reaction mechanism
From the alkyne is prepared in situ the metal acetylide which reacts with the carbon atom of the carbonyl group. This requires strong bases such as a hydroxide or an alkoxide. When the reaction product (a Propargyl alcohol) contains a proton alpha to the alcohol group (which is the case when the carbonyl is an aldehyde), it will tautomerize to the corresponding enone.

This reaction is used as a protect alkynes: the alkyne is either converted with acetone to a 2-hydroxyprop-2-yl-alkyne or converted directly with the commercially available 3-methyl-1-butyne-3-ol also to a protected alkyne. The protective group can be removed by heating the compound in a solution of potassium hydroxide in isopropanol (a retro-Favorskii reaction).