1: 95 percent / 0.05N H2SO4 / H2O / 5 h / 50 °C 2: triethylamine / acetonitrile / -15 deg C, 1h, then 20 deg C, 2 h, then 50 deg C, 12 h 3: 71 percent / p-toluenesulfonic acid, NaI / H2O; CHCl3 / 4 h / 0 °C 4: NaOMe / 0.5 h / -20 °C View Scheme

Multi-step reaction with 3 steps 1: triethylamine / methanol / 1 h / 20 °C2: 1.) p-toluenesulfonic acid; 2.) p-toluenesulfonic acid, NaI/H2O / 1.) chloroform, 0 --> 20 deg C, 1 h; 2.) chloroform, reflux, 12 h3: 92 percent / Na2(OCH2)2 / 48 h / 20 °C  

Multi-step reaction with 4 steps 1: 0.05N H2SO4 / H2O / 5 h / 50 °C2: triethylamine / -15 deg C, 5h, then 50 deg C, 14 h3: 1.) p-toluenesulfonic acid; 2.) p-toluenesulfonic acid, NaI/H2O / 1.) chloroform, 0 --> 20 deg C, 1 h; 2.) chloroform, reflux, 12 h4: 92 percent / Na2(OCH2)2 / 48 h / 20 °C  

Multi-step reaction with 4 steps 1: 95 percent / 0.05N H2SO4 / H2O / 5 h / 50 °C2: triethylamine / acetonitrile / -15 deg C, 1h, then 20 deg C, 2 h, then 50 deg C, 12 h3: 1.) p-toluenesulfonic acid; 2.) p-toluenesulfonic acid, NaI/H2O / 1.) chloroform, 0 --> 20 deg C, 1 h; 2.) chloroform, reflux, 12 h4: 92 percent / methanol / 48 h / 20 °C  

With  sulfuric acid in  water T=50°C; 5 h;   

Multi-step reaction with 5 steps 1: 95 percent / 0.05N H2SO4 / H2O / 5 h / 50 °C2: triethylamine / acetonitrile / -15 deg C, 1h, then 20 deg C, 2 h, then 50 deg C, 12 h3: 1.) p-toluenesulfonic acid; 2.) p-toluenesulfonic acid, NaI/H2O / 1.) chloroform, 0 --> 20 deg C, 1 h; 2.) chloroform, reflux, 12 h4: 97 percent / NaH / 48 h / 20 °C5: 94 percent / 0.05N H2SO4 / H2O / 5 h / 50 °C  

Multi-step reaction with 3 steps 1: 95 percent / 0.05N H2SO4 / H2O / 5 h / 50 °C2: triethylamine / acetonitrile / -15 deg C, 1h, then 20 deg C, 2 h, then 50 deg C, 12 h3: 71 percent / p-toluenesulfonic acid, NaI / H2O; CHCl3 / 4 h / 0 °C