oxygen; copper(l) chloride; palladium dichloride in water; N,N-dimethyl-formamide T=50°C; Yield given. Title compound not separated from byproducts;

1: CuCl, O2 / PdCl2 / dimethylformamide; H2O / 50 °C 2: 1.) NaOH aq., 2.) pyridinium chlorochromate View Scheme