Pd(II)-catalyzed ortho-C-H oxidation of arylacetic acid derivatives: synthesis of benzofuranones.

Pd(II)-catalyzed ortho-C-H acetoxylation of arylacetic acid derivatives is demonstrated with the aid of a novel S-methyl-S-2-pyridylsulfoximine (MPyS) directing group (DG). The α-mono- and α-unsubstituted arylacetic acid derivatives were readily employed in the ortho-C-H acetoxylations. The oxidation products are hydrolyzed, and the MPyS-DG is easily recovered, providing ready access to o-hydroxyarylacetic acids. 3-Mono- and 3-unsubstituted benzofuranones are synthesized from o-hydroxyarylacetic acids.