4-Aryl-2-quinolones Through Heck and Buchwald-Hartwig Reaction

Significance

An interesting sequence involving Heck and Buchward-Hartwig coupling processes on 2-bromocinnamamide with a variety of aryl iodides and bromides under palladium(II) acetate catalysis in molten tetra(n-butyl)ammonium acetate/tetra(n-butyl)ammonium bromide to give 4-aryl-2-quinolones in moderate yields is reported. The Heck reaction precedes the C-N bond-forming step. The expected competitive intramolecular N-arylation was not observed. Interestingly, although the Heck reaction may be independently achieved without use of molten salts, treatment of the product under the typical conditions failed to give the quinolone product. Furthermore, treatment of 2-quinolone with an aryl iodide did not afford the Heck product. The scope of the reaction was modestly tested with aryl iodides bearing EWGs and EDGs.