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.^[1]

Additional recommended knowledge

How to quickly check pipettes?

What is the Sensitivity of my Balance?

Safe Weighing Range Ensures Accurate Results

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

Reaction mechanism

A metal acetylide is formed in situ when an alkyne is treated with a strong bases such as a hydroxide or an alkoxide. The metal acetylide then reacts with an aldehyde or ketone to form a propargyl alcohol. When an alpha hydrogen is present (as 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).^[2]

References