1: 90 percent / POCl3 / toluene 2: 81 percent / BBr3 / CH2Cl2 / -70 °C 3: 1) K2CO3, 2) Ac2O / 1) acetone, 4 h then RT, overnight, 2) reflux, 1 h View Scheme

acetic anhydride; potassium carbonate 1) acetone, 4 h then RT, overnight, 2) reflux, 1 h; Yield given. Multistep reaction;