1: n-BuLi / hexane; tetrahydrofuran / 1 h / Ambient temperature 2: concentrated H2SO4 / tetrahydrofuran; hexane / 1 h / Heating 3: p-toluenesulfonic acid monohydrate / Ambient temperature 4: n-BuLi / hexane; tetrahydrofuran / 1 h / -70 °C 5: concentrated HCl / tetrahydrofuran / Ambient temperature View Scheme

Multi-step reaction with 2 steps 1: n-BuLi / hexane; tetrahydrofuran / 1 h / Ambient temperature2: concentrated H2SO4 / tetrahydrofuran; hexane / 1 h / Heating