1: 1.) pyridinium dichromate; 2.) DCC, 4-DMAP / 1.) DMF, 15 h, 40 deg C; 2.) CH2Cl2, 3 h, room temperature 2: 69 percent / TEA, benzyl alcohol / 24 h / 105 °C 3: hydrogen / 10percent Pd/C / ethanol / Ambient temperature 4: 90 percent / TFA / CH2Cl2 / 0.5 h / Ambient temperature View Scheme

Multi-step reaction with 3 steps 1: 90 percent / RuO2 hydrate, 10percent aqueous NaIO4 / ethyl acetate / 1 h / Ambient temperature2: 1.) n-butyllithium, diisopropylamine / 1.) THF, -78 deg C, 30 min; 2.) THF, -78 deg C, 1h; 3.) room temperature, 1h3: 78 percent / p-toluenesulphonic acid / methanol / 2 h / Ambient temperature  

Multi-step reaction with 2 steps 1: 1.) n-butyllithium, diisopropylamine / 1.) THF, -78 deg C, 30 min; 2.) THF, -78 deg C, 1h; 3.) room temperature, 1h2: 78 percent / p-toluenesulphonic acid / methanol / 2 h / Ambient temperature