boron trifluoride diethyl etherate in diethyl ether T=-5°C; 0.5 h; Yield given. Yields of byproduct given. Title compound not separated from byproducts;

1: 82 percent / m-perbenzoic acid / CH2Cl2 / 12 h 2: borontrifluoride etherate / diethyl ether / 0.5 h / -5 °C View Scheme