Synthesis of 2-Quinolones via Intramolecular Olefination

Significance

Reported here is a one-pot synthesis of 2-quinolones by acylation of o-aminophenyl ketones A with substituted diethyl phosphono­acetyl chloride (or corresponding carboxylic acid) B followed by an intramolecular Horner-Wads­worth-Emmons (HWE) olefination in good yields under mild reaction conditions. In case of acid B (and acid-sensitive compounds, for example, with R^³ = NHBoc), the process was carried out in two steps: first an EDC-mediated coupling to give the amide formation followed by a HWE olefination. The synthesis of a thoughtful selection of 2-quinolones was demonstrated.