A simple method for performing ?-C-alkylation of acetoacetate esters using equilibrating bases (carbonate and alkoxide salts) has been developed.  This reaction is unusual because similar reaction conditions have been used to generate enones via a Knoevenagel condensation reaction. When a substituted benzaldehyde was used as the electrophile, either a 5-aryl-5-hydroxy-3-oxopentanoate ester or a 5-aryl-3-oxo-d-lactone was generated depending the solvent that was used. Deuterium exchange, carbon-13 labeling, and variable temperature 1H NMR experiments indicate that the mechanism for the formation of the d-lactones proceeds by deprotonation at carbon-4 of the acetoacetate ester, addition of the resulting enolate ion of the acetoacetate ester to the benzaldehyde, followed by an intramolecular transesterification of the resulting hydroxyketoester intermediate. In addition to the mechanistic results, data from scope and limitation studies on the effects of aromatic substituents and acetoacetate substituents will be presented.

γ-C-Alkylation of acetoacetate esters using equilibrating bases

239th National Meeting (2010)

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