1: With titanium(IV) isopropylate in tetrahydrofuran; diethyl ether T=20°C; 1 h; 2: With boron trifluoride diethyl etherate in tetrahydrofuran; diethyl ether 1 h; 3: With sodium hydroxide; water in tetrahydrofuran; diethyl ether

1: With titanium(IV) isopropylate in tetrahydrofuran T=20°C; 1 h; 2: With boron trifluoride diethyl etherate in diethyl ether T=20°C; 0.5 h; 3: With sodium hydroxide Further stages.;