1: With sodium hydroxide; water T=45°C; 3 h; 2: With hydrogenchloride in water T=0°C;

1.1: NaOH / ethanol 1.2: triphosgene / tetrahydrofuran / 45 °C 1.3: 84 percent / HCl / diethyl ether / 24 h 2.1: 85 percent / Cs2CO3 / dimethylformamide; tetrahydrofuran / 20 °C 3.1: CH3COOH / CH2Cl2 / 24 h 3.2: 90 percent / TFA / CH2Cl2 / 0.5 h 4.1: PhSH; NaH / 1,2-dimethoxy-ethane / 8 h / 20 °C 4.2: m-CPBA / CH2Cl2 / -78 °C 4.3: 64 percent / Na2CO3 / toluene / Heating 5.1: 75 percent / Ni(COD)2 / acetonitrile / 0.5 h / 20 °C 6.1: 70 percent / H2 / Crabtree's catalyst / 760.05 Torr 7.1: DMAP / tetrahydrofuran / 91 h View Scheme