Metal Duo Makes β-Aryl Ketones

The carbons immediately adjacent to a carbonyl group are usually straightforward places to form new carbon-carbon bonds. Just use a strong base, or a carefully designed catalyst, and that α-carbon is good to go. The next carbon over, the β-carbon, is not so amenable to change, however. Traditionally, β-substituted carbonyls require multiple steps to prepare. Because that β-motif is common in insecticides and drug candidates, chemists are keen to simplify the process. They’ve developed a handful of β-functionalization reactions, but none is generally applicable yet. Now, graduate student Zhongxing Huang and assistant professor Guangbin Dong of the University of Texas, Austin, have added to the toolbox with a reaction that inserts aromatic rings at the β-position of simple ketones (J. Am. Chem. Soc. 2013, DOI: 10.1021/ja410389a). The palladium-catalyzed process uses readily available aryl iodides and bromides as the substrates. A silver salt regenerates the active catalyst. Dong cautions that the reaction is still in its infancy. He’d like to figure out the reaction mechanism and replace the silver reagent with something less expensive. UT Austin is pursuing a provisional patent on the chemistry.