Simple Method For Aryl Methyl Ketones

Palladium-catalyzed cross-couplings are workhorse reactions for generating new C–C bonds in organic synthesis, with most methods focusing on aryl-aryl or aryl-alkene coupling. Fewer examples of cross-couplings to build aryl-carbonyl linkages are known, and they typically combine an aryl halide with a vinylstannane. Taking an alternative approach, UCLA chemists Stephen D. Ramgren and Neil K. Garg have developed an aryl-carbonyl cross-coupling process to make aryl methyl ketones using low-cost acetyltrimethylsilane as a coupling partner for aryl and heteroaryl bromides (Org. Lett. 2014, DOI: 10.1021/ol403570z). Using cesium fluoride to activate the silane and trap the silyl group, the researchers made a variety of aryl methyl ketones, including some examples that would be difficult to achieve with standard Friedel-Crafts reaction chemistry. To demonstrate the usefulness of the reaction for drug discovery, the UCLA team coupled the silane with a heterocyclic substrate and prepared an acetylated estrone derivative. The new approach is already garnering attention from industrial and academic chemists, Garg says, because it’s a simpler and greener option to known coupling methods to make aryl methyl ketones.