1: boron trifluoride etherate / CH2Cl2 / -78 deg C, then room temperature 2: 100.4 mg / trifluoroacetic acid / CH2Cl2 / 4 h / Ambient temperature View Scheme

Multi-step reaction with 2 steps 1: 81 percent / PPTS / benzene / 3 h / Heating2: boron trifluoride etherate / CH2Cl2  

With  pyridinium p-toluenesulfonate; 3-hydroxy-2,2-dimethylpropanol in  benzene  Heating;