Regioselective, directed meta acylation of aromatic compounds

A new method for the directed meta acylation of aromatic compounds is described. This method involves an ortho lithiation procedure combined with zirconocene-benzyne chemistry. 3-Acyl-1-substituted benzene derivatives were obtained by acidic hydrolysis of the azazirconacycle intermediate which results from the coupling of a nitrile with a zirconocene-benzyne complex. Similarly, 3-acyl-2-iodo-1-substituted benzene derivatives were obtained by the iodination of the same intermediate followed by acidic hydrolysis. These procedures, which utilize simple, readily available starting materials, give good yields of regiochemically pure products.