boron trifluoride diethyl etherate in chloroform 0 deg C, 1 h, -> RT, 5 h;

1: 91 percent / Et3N / CH2Cl2 / 5 h / Ambient temperature 2: 100 percent / BF3*Et2O / CHCl3 / 0 deg C, 1 h, -> RT, 5 h View Scheme

1: 1.) NH4Cl, NH4OH, 2.) HCl gas / 1.) H2O-Et2O, RT, 2.) Et2O, 0 deg C 2: 91 percent / Et3N / CH2Cl2 / 5 h / Ambient temperature 3: 100 percent / BF3*Et2O / CHCl3 / 0 deg C, 1 h, -> RT, 5 h View Scheme