1: 83 percent / tri-n-butyltin hydride / tetrahydrofuran; benzene / 0.5 h / Ambient temperature 2: chromium trioxide, sulphuric acid / acetone; H2O / 1.) 5 deg C, 2 h, 2.) room temperature, 2 h View Scheme

tri-n-butyl-tin hydride in tetrahydrofuran; benzene 0.5 h; Ambient temperature;