1: 65 percent / tetrahydrofuran / RT, 1 h; 40 deg C, 2 h; 50 deg C, 1 h 2: 71 percent / potassium hydroxide / ethane-1,2-diol / 8 h / Heating View Scheme

4 A molecular sieve; boron trifluoride diethyl etherate in benzene 68 h; Heating;