Favorskii reaction

The reaction was discovered in the early 1900s by the Russian chemist Alexei Yevgrafovich Favorskii.

[1] When the carbonyl is an aldehyde (R"=H), a rearrangement can occur to generate enone, although the secondary propargylic alcohol can be isolated in some cases.

Successful reactions with aldehydes often require special solvents to be used, such as DMSO[4] or 1,2-dimethoxyethane with a trace amount of ethanol.

Hydroxide bases are inexpensive relative to generating an alkoxide or acetylide with reagents such as elemental lithium, sodium, or potassium.

[5] The protective group can be removed by heating the compound in a solution of potassium hydroxide in propan-2-ol (a retro-Favorskii reaction).