1: 97 percent / aq. AcOH / tetrahydrofuran / 40 h / Ambient temperature 2: 80 percent / CdCO3 / toluene / 2.5 h / Heating 3: 65 percent / aq. NaOH / methanol / 24 h / Ambient temperature View Scheme

With  acetic anhydride in  pyridine Show Experimental Procedure  

With  acetic acid in  tetrahydrofuran 40 h;  Ambient temperature;