acetic acid T=0°C; 24 h;

1.1: boron trifluoride diethyl etherate / 20 h / 0 °C 2.1: sodium methylate / methanol / 24 h / 20 °C 2.2: Amberlyst 15.(TM). / 0.08 h 3.1: toluene-4-sulfonic acid / N,N-dimethyl-formamide / 24 h / 20 °C View Scheme