Palladium-Catalyzed Intermolecular Directed C-H Amidation of Aromatic Ketones

Pd-catalyzed directed ortho C-H amidation of aromatic ketones with both sulfonamides and amides has been accomplished. The use of an electron-deficient Pd complex, Pd(OTf)(2), is crucial for the success of this transformation. Some key intermediates of the reaction, that is, the cyclopalladation complexes of ketones, have been characterized by X-ray crystallography. Experimental analysis of these palladacycles and also the experimental results with N-methyl sulfonamides indicate that the new reaction does not seem to proceed through a nitrene intermediate. The utility of the newly developed reaction was demonstrated for the synthesis of useful organic intermediates such as 2- and 3-alkyl indoles and 2-aminophenyl ketones.