Favorskii Reaction

The rearrangement of cyclopropanones, often obtained as intermediates from the base-catalyzed reaction of α-halo ketones, leading to carboxylic acids and derivatives.

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Mechanism of the Favorskii Reaction

Esters are obtained if alkoxide bases are used:

A direct conversion from α-halo ketones is possible:

Ring-contraction:

Recent Literature

Nickel-Catalyzed Favorskii-Type Rearrangement of Cyclobutanone Oxime Esters to Cyclopropanecarbonitriles
B. Shuai, P. Fang, T.-S. Mei, Synlett, 2021, 32, 1637-1641.

Halocycloalkenones as Diels-Alder Dienophiles. Applications to Generating Useful Structural Patterns
A. G. Ross, S. D. Townsend, S. J. Danishefsky, J. Org. Chem., 2013, 78, 204-210.