1: With n-butyllithium in diethyl ether; hexane T=-78°C; 0.666667 h; 2: With boron triethoxide in diethyl ether; hexane T=-78°C; 4.16667 h; 3: With hydrogenchloride; water in diethyl ether; hexane T=20°C; 17.5 h; Heating / reflux;