toluene-4-sulfonic acid in methanol; chloroform 24 h; Ambient temperature;

1: pyridine / 5 h / 70 °C 2: 1.) NaH / 1.) THF, RT, 30 min, 2.) THF, RT, overnight 3: 63 percent / BF3*2MeOH / CH2Cl2 / 2 h / 0 °C View Scheme

1: 1.) NaH / 1.) THF, RT, 30 min, 2.) THF, RT, overnight 2: 63 percent / BF3*2MeOH / CH2Cl2 / 2 h / 0 °C View Scheme

1: 95 percent / KOH / aq. ethanol / 24 h / Ambient temperature 2: 94 percent / pyridine / 36 h / Ambient temperature 3: 1.) NaH / 1.) THF, RT, 1 h, 2.) RT, 24 h 4: 89 percent / p-toluenesulfonic acid / CHCl3; methanol / 24 h / Ambient temperature View Scheme