1: 76 percent / acetic anhydride / 4 h 2: 52 percent / Na2CO3, tetrabutylammonium bromide / H2O; CH2Cl2 / 2 h / Ambient temperature 3: 47 percent / p-toluenesulfonic acid / methanol / 3 h / Heating View Scheme

 in  acetic anhydride 4 h;   

Multi-step reaction with 2 steps 1: 76 percent / acetic anhydride / 4 h2: 52 percent / Na2CO3, tetrabutylammonium bromide / H2O; CH2Cl2 / 2 h / Ambient temperature  

Multi-step reaction with 3 steps 1: 76 percent / acetic anhydride / 4 h2: 52 percent / Na2CO3, tetrabutylammonium bromide / H2O; CH2Cl2 / 2 h / Ambient temperature3: 79 percent / p-toluenesulfonic acid / methanol / 3 h / Heating