Pd(II)-Catalyzed ortho-C–H Oxidation of Arylacetic Acid Derivatives: Synthesis of Benzofuranones
摘要:
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 alpha-mono- and alpha-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 0-hydroxyarylacetic acids. 3-Mono- and 3-unsubstituted benzofuranones are synthesized from 0-hydroxyarylacetic acids.
The N-acylation of a sulfoximine with carboxylic acids was accomplished with boric acid and several boronic acids. Aliphatic acids give fair yields of products while acids related to phenylacetic and phenoxyacetic acids perform much better. Aromatic acids are ineffective in this process.