potassium carbonate; caesium carbonate in dimethyl sulfoxide; acetonitrile T=65°C; 24 h;

1: 89 percent / p-TsOH, molecular sieves / CCl4 2: 63 percent / K2CO3, Cs2CO3 / acetonitrile; dimethylsulfoxide / 24 h / 65 °C View Scheme