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