1.1: sodium hydride / N,N-dimethyl-formamide; mineral oil / 1 h / Cooling with ice 1.2: 4.5 h / 20 °C 2.1: n-butyllithium / tetrahydrofuran; hexane / 1 h / -78 °C / Inert atmosphere 2.2: 3.5 h / -78 - 20 °C / Inert atmosphere 3.1: hydrogenchloride / 1,4-dioxane / 3 h / 20 °C 4.1: methanesulfonic acid / toluene View Scheme

1.1: sodium hydride / N,N-dimethyl-formamide; mineral oil / 1 h / Cooling with ice 1.2: 4.5 h / 20 °C 2.1: n-butyllithium / tetrahydrofuran; hexane / 1 h / -78 °C / Inert atmosphere 2.2: 3.5 h / -78 - 20 °C / Inert atmosphere 3.1: hydrogenchloride / 1,4-dioxane / 3 h / 20 °C 4.1: methanesulfonic acid / toluene View Scheme