1: 80.5 percent / p-toluenesulfonic acid / methanol / 3 h / 25 °C 2: 73 percent / pyridine / 0 °C 3: 95 percent / p-toluenesulfonic acid / CH2Cl2 / 1 h / 25 °C 4: 78 percent / NaI, azoisobutyronitrile, Bu3SnH / bis-(2-methoxy-ethyl) ether / 1.5 h / Heating 5: 94 percent / H+ ion-exchange resin (Amberlyst 15), 4-A molecular sieves / acetonitrile / 4 h / 25 °C View Scheme

Multi-step reaction with 3 steps 1: 80.5 percent / p-toluenesulfonic acid / methanol / 3 h / 25 °C2: 73 percent / pyridine / 0 °C3: 95 percent / p-toluenesulfonic acid / CH2Cl2 / 1 h / 25 °C  

Multi-step reaction with 4 steps 1: 80.5 percent / p-toluenesulfonic acid / methanol / 3 h / 25 °C2: 73 percent / pyridine / 0 °C3: 95 percent / p-toluenesulfonic acid / CH2Cl2 / 1 h / 25 °C4: 78 percent / NaI, azoisobutyronitrile, Bu3SnH / bis-(2-methoxy-ethyl) ether / 1.5 h / Heating