1: 1) 70percent HClO4, 2) DDQ / 1) CCl4, RT, 3 h, 2) benzene, RT, 3.5 h 2: 232 mg / NaOMe / methanol / 0.25 h / Ambient temperature View Scheme

1: hexamethyldisilazane / CH2Cl2 / 1.) -10 deg C, 1 h, 2.) room temperature 2: 80 mg / N-methylmorpholine N-oxide hydrate, OsO4 / Triton B / 2-methyl-propan-2-ol; H2O / 1.67 h / 10 °C 3: 482 mg / dichlorodicyanobenzoquinone / benzene / 24 h / Ambient temperature 4: 37.6 percent / EtSH, AlCl3 / CH2Cl2 / 2 h / Ambient temperature View Scheme