1: With lithium hydroxide hydrate in tetrahydrofuran; water 18 h; 2: With hydrogenchloride in tetrahydrofuran; diethyl ether; water pH=2 - 3;

potassium hydroxide in methanol T=20°C;

1H-imidazole in N,N-dimethyl-formamide 48 h; Ambient temperature;

1: 95 percent / imidazole / dimethylformamide / 20 °C 2: 82 percent / KOH / methanol / 20 °C View Scheme

1: 93 percent / silver tetrakis[3,5-bis(trifluoromethyl)phenyl]borate / zirconocene dichloride / CH2Cl2; diethyl ether / 6 h / -78 °C 2: zirconocene dichloride; silver perchlorate; 4-methyl-1-propyl-2,6,7-trioxabicyclo[2.2.2]octane / CH2Cl2 / 1 h / 0 - 22 °C 3: 17 mg / aq. LiOH / tetrahydrofuran / 4 h / 22 °C View Scheme

1: 52 percent / aq. H2SO4 / tetrahydrofuran / 4 h / 50 °C 2: 98 percent / triethylamine / CH2Cl2 / 0.25 h / -10 °C 3: 86 percent / 1,8-diazabicyclo[5.4.0]undec-7-ene / CH2Cl2 / 0.17 h / 22 °C 4: 93 percent / silver tetrakis[3,5-bis(trifluoromethyl)phenyl]borate / zirconocene dichloride / CH2Cl2; diethyl ether / 6 h / -78 °C 5: zirconocene dichloride; silver perchlorate; 4-methyl-1-propyl-2,6,7-trioxabicyclo[2.2.2]octane / CH2Cl2 / 1 h / 0 - 22 °C 6: 17 mg / aq. LiOH / tetrahydrofuran / 4 h / 22 °C View Scheme

1: 86 percent / 1,8-diazabicyclo[5.4.0]undec-7-ene / CH2Cl2 / 0.17 h / 22 °C 2: 93 percent / silver tetrakis[3,5-bis(trifluoromethyl)phenyl]borate / zirconocene dichloride / CH2Cl2; diethyl ether / 6 h / -78 °C 3: zirconocene dichloride; silver perchlorate; 4-methyl-1-propyl-2,6,7-trioxabicyclo[2.2.2]octane / CH2Cl2 / 1 h / 0 - 22 °C 4: 17 mg / aq. LiOH / tetrahydrofuran / 4 h / 22 °C View Scheme

1: zirconocene dichloride; silver perchlorate; 4-methyl-1-propyl-2,6,7-trioxabicyclo[2.2.2]octane / CH2Cl2 / 1 h / 0 - 22 °C 2: 17 mg / aq. LiOH / tetrahydrofuran / 4 h / 22 °C View Scheme