1: 90 percent / Et3N / CH2Cl2 2: 96 percent / H2O2 / tetrahydrofuran / Ambient temperature 3: 1.) NaIO4 / 2.) pyrolysis View Scheme

With  potassium hydroxide in  methanol; water  Heating;   

Multi-step reaction with 2 steps 1: 92 percent / SnCl4 / CH2Cl2 / 1.) -78 deg C, 2.) room temperature2: 78 percent / KOH / methanol; H2O / Heating