Ketones from Aryl Halides and Aliphatic Aldehydes by Direct Acylation

The group of JianLiang Xiao at the University of Liverpool has recently published (Ruan J et al, J Am Chem Soc, 2008, 130, 10510-10511) the first report of a palladium catalysed method for a new acylation method, which promises to be very useful in process chemistry (see scheme).  The reaction works for a variety of aldehydes, including some with additional ester functionality, and with a variety of aryl bromides, including those with F groups in the ring.  The reaction works best in DMF; poor results were obtained in dioxane and toluene.

It is envisaged that the reaction proceeds via arylation of the enol form of the aldehyde.  The methodology avoids the disadvantage of previous Heck-type strategies from the group of Xiao such as arylation of enamines, where the enamine has to be separately prepared.  (Hyder Z et al, ChemEur J, 2008, 14, 5555).