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.

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

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.