1: 92 percent / pyridinium p-toluenesulfonate / CHCl3 / 1 h / 20 °C 2: 62 percent / NaBH4 / 1,2-dimethoxy-ethane / 1 h / 20 °C 3: Et3N / benzene 4: acetonitrile / 24 h / 65 °C 5: 98 percent / HCl / dioxane; H2O View Scheme

1: 92 percent / pyridinium p-toluenesulfonate / CHCl3 / 1 h / 20 °C 2: 62 percent / NaBH4 / 1,2-dimethoxy-ethane / 1 h / 20 °C 3: Et3N / benzene 4: acetonitrile / 24 h / 65 °C 5: 98 percent / HCl / dioxane; H2O View Scheme

1: 92 percent / pyridinium p-toluenesulfonate / CHCl3 / 1 h / 20 °C 2: 62 percent / NaBH4 / 1,2-dimethoxy-ethane / 1 h / 20 °C 3: 58 percent / tetrazole / acetonitrile; CHCl3 / 48 h / 20 °C 4: 90 percent / aq. H2O2 / CH2Cl2 5: 70 percent / DBU / toluene / 16 h / 110 °C 6: 86 percent / HCl / dioxane; H2O View Scheme