p-toluenesulfonic acid monohydrate in tetrahydrofuran; ethyl acetate

water; toluene-4-sulfonic acid in acetone 24 h; Heating;

1.1: t-BuLi / diethyl ether; pentane / 1 h / -78 °C 1.2: diethyl ether; pentane / 12 h / 20 °C 2.1: p-TsOH; H2O / acetone / 24 h / Heating View Scheme

1.1: 90 percent / p-TsOH 2.1: t-BuLi / diethyl ether; pentane / 1 h / -78 °C 2.2: diethyl ether; pentane / 12 h / 20 °C 3.1: p-TsOH; H2O / acetone / 24 h / Heating View Scheme