Catalytic Oxidation of 3‑Arylbenzofuran-2(3<i>H</i>)‑ones with PCC‑H₅IO₆: Syntheses of 3‑Aryl-3-hydroxy/3-amido-3-arylbenzofuran-2(3<i>H</i>)‑ones

A pyridinium chlorochromate (PCC)-mediated facile oxidative dimerization of 3-arylbenzofuran-2-ones at ambient temperature was developed which undergo oxidative cleavage to 3-aryl-3-hydroxy-benzofuran-2-ones with PCC at elevated temperatures. Finally, direct oxidation of 3-arylbenzofuran-2-ones to 3-aryl-3-hydroxy-benzofuran-2-ones was realized using a combination of PCC (10 mol %) and 2.0 equiv of H5IO6. The synthesized 3-aryl-3-hydroxy-benzofuranones were further converted to corresponding 3-amido-3-aryl-benzofuranones in high yields by Ritter reaction. Thus, the present protocol provides a nonconventional approach to C-3 hydroxylation of 3-arylbenzofuranones via their dimer using a catalytic amount of inexpensive chromium­(VI) oxidant.