1: 70 percent HClO4 / diethyl ether / 0.67 h / - 30 deg C to RT 2: K-hexamethyldisilazide / 1.) THF, toluene, 20 min, RT, 2.) a) -78 deg C, b) RT, 30 min 3: 91 percent / Na, liq. NH3 / tetrahydrofuran / 1 h / -78 °C 4: pyridinium dichromate / dimethylformamide / 1.) 0 deg C, 1 h, 2.) RT, 4 h 5: diethyl ether 6: 0.1 N HCl / methanol / 24 h View Scheme